﻿/********************************************************
 * ADO.NET 2.0 Data Provider for SQLite Version 3.X
 * Written by Robert Simpson (robert@blackcastlesoft.com)
 * 
 * Released to the public domain, use at your own risk!
 ********************************************************/

namespace System.Data.SQLite
{
  using System;
  using System.Data;
  using System.Data.Common;
  using System.Collections.Generic;
  using System.Globalization;
  using System.ComponentModel;
  using System.Text;
  using System.Runtime.InteropServices;
  using System.IO;

  /// <summary>
  /// SQLite implentation of DbConnection.
  /// </summary>
  /// <remarks>
  /// The <see cref="ConnectionString">ConnectionString</see> property of the SQLiteConnection class can contain the following parameter(s), delimited with a semi-colon:
  /// <list type="table">
  /// <listheader>
  /// <term>Parameter</term>
  /// <term>Values</term>
  /// <term>Required</term>
  /// <term>Default</term>
  /// </listheader>
  /// <item>
  /// <description>Data Source</description>
  /// <description>{filename}</description>
  /// <description>Y</description>
  /// <description></description>
  /// </item>
  /// <item>
  /// <description>Version</description>
  /// <description>3</description>
  /// <description>N</description>
  /// <description>3</description>
  /// </item>
  /// <item>
  /// <description>UseUTF16Encoding</description>
  /// <description><b>True</b><br/><b>False</b></description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// <item>
  /// <description>DateTimeFormat</description>
  /// <description><b>Ticks</b> - Use DateTime.Ticks<br/><b>ISO8601</b> - Use ISO8601 DateTime format</description>
  /// <description>N</description>
  /// <description>ISO8601</description>
  /// </item>
  /// <item>
  /// <description>BinaryGUID</description>
  /// <description><b>True</b> - Store GUID columns in binary form<br/><b>False</b> - Store GUID columns as text</description>
  /// <description>N</description>
  /// <description>True</description>
  /// </item>
  /// <item>
  /// <description>Cache Size</description>
  /// <description>{size in bytes}</description>
  /// <description>N</description>
  /// <description>2000</description>
  /// </item>
  /// <item>
  /// <description>Synchronous</description>
  /// <description><b>Normal</b> - Normal file flushing behavior<br/><b>Full</b> - Full flushing after all writes<br/><b>Off</b> - Underlying OS flushes I/O's</description>
  /// <description>N</description>
  /// <description>Normal</description>
  /// </item>
  /// <item>
  /// <description>Page Size</description>
  /// <description>{size in bytes}</description>
  /// <description>N</description>
  /// <description>1024</description>
  /// </item>
  /// <item>
  /// <description>Password</description>
  /// <description>{password}</description>
  /// <description>N</description>
  /// <description></description>
  /// </item>
  /// <item>
  /// <description>Enlist</description>
  /// <description><b>Y</b> - Automatically enlist in distributed transactions<br/><b>N</b> - No automatic enlistment</description>
  /// <description>N</description>
  /// <description>Y</description>
  /// </item>
  /// <item>
  /// <description>Pooling</description>
  /// <description><b>True</b> - Use connection pooling<br/><b>False</b> - Do not use connection pooling</description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// <item>
  /// <description>FailIfMissing</description>
  /// <description><b>True</b> - Don't create the database if it does not exist, throw an error instead<br/><b>False</b> - Automatically create the database if it does not exist</description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// <item>
  /// <description>Max Page Count</description>
  /// <description>{size in pages} - Limits the maximum number of pages (limits the size) of the database</description>
  /// <description>N</description>
  /// <description>0</description>
  /// </item>
  /// <item>
  /// <description>Legacy Format</description>
  /// <description><b>True</b> - Use the more compatible legacy 3.x database format<br/><b>False</b> - Use the newer 3.3x database format which compresses numbers more effectively</description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// <item>
  /// <description>Default Timeout</description>
  /// <description>{time in seconds}<br/>The default command timeout</description>
  /// <description>N</description>
  /// <description>30</description>
  /// </item>
  /// <item>
  /// <description>Journal Mode</description>
  /// <description><b>Delete</b> - Delete the journal file after a commit<br/><b>Persist</b> - Zero out and leave the journal file on disk after a commit<br/><b>Off</b> - Disable the rollback journal entirely</description>
  /// <description>N</description>
  /// <description>Delete</description>
  /// </item>
  /// <item>
  /// <description>Read Only</description>
  /// <description><b>True</b> - Open the database for read only access<br/><b>False</b> - Open the database for normal read/write access</description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// <item>
  /// <description>Max Pool Size</description>
  /// <description>The maximum number of connections for the given connection string that can be in the connection pool</description>
  /// <description>N</description>
  /// <description>100</description>
  /// </item>
  /// <item>
  /// <description>Default IsolationLevel</description>
  /// <description>The default transaciton isolation level</description>
  /// <description>N</description>
  /// <description>Serializable</description>
  /// </item>
  /// <item>
  /// <description>Foreign Keys</description>
  /// <description>Enable foreign key constraints</description>
  /// <description>N</description>
  /// <description>False</description>
  /// </item>
  /// </list>
  /// </remarks>
  public sealed partial class SQLiteConnection : DbConnection, ICloneable
  {
    private const string _dataDirectory = "|DataDirectory|";
    private const string _masterdb = "sqlite_master";
    private const string _tempmasterdb = "sqlite_temp_master";

    /// <summary>
    /// State of the current connection
    /// </summary>
    private ConnectionState _connectionState;
    /// <summary>
    /// The connection string
    /// </summary>
    private string _connectionString;
    /// <summary>
    /// Nesting level of the transactions open on the connection
    /// </summary>
    internal int _transactionLevel;

    /// <summary>
    /// The default isolation level for new transactions
    /// </summary>
    private IsolationLevel _defaultIsolation;

#if !PLATFORM_COMPACTFRAMEWORK
    /// <summary>
    /// Whether or not the connection is enlisted in a distrubuted transaction
    /// </summary>
    internal SQLiteEnlistment _enlistment;
#endif
    /// <summary>
    /// The base SQLite object to interop with
    /// </summary>
    internal SQLiteBase _sql;
    /// <summary>
    /// The database filename minus path and extension
    /// </summary>
    private string _dataSource;
    /// <summary>
    /// Temporary password storage, emptied after the database has been opened
    /// </summary>
    private byte[] _password;

    /// <summary>
    /// Default command timeout
    /// </summary>
    private int _defaultTimeout = 30;

    internal bool _binaryGuid;

    internal long _version;

    private event SQLiteUpdateEventHandler _updateHandler;
    private event SQLiteCommitHandler _commitHandler;
    private event SQLiteTraceEventHandler _traceHandler;
    private event EventHandler _rollbackHandler;

    private SQLiteUpdateCallback _updateCallback;
    private SQLiteCommitCallback _commitCallback;
    private SQLiteTraceCallback _traceCallback;
    private SQLiteRollbackCallback _rollbackCallback;

    /// <summary>
    /// This event is raised whenever the database is opened or closed.
    /// </summary>
    public override event StateChangeEventHandler StateChange;

    ///<overloads>
    /// Constructs a new SQLiteConnection object
    /// </overloads>
    /// <summary>
    /// Default constructor
    /// </summary>
    public SQLiteConnection()
      : this("")
    {
    }

    /// <summary>
    /// Initializes the connection with the specified connection string
    /// </summary>
    /// <param name="connectionString">The connection string to use on the connection</param>
    public SQLiteConnection(string connectionString)
    {
      _connectionState = ConnectionState.Closed;
      _connectionString = "";
      //_commandList = new List<WeakReference>();

      if (connectionString != null)
        ConnectionString = connectionString;
    }

    /// <summary>
    /// Clones the settings and connection string from an existing connection.  If the existing connection is already open, this
    /// function will open its own connection, enumerate any attached databases of the original connection, and automatically
    /// attach to them.
    /// </summary>
    /// <param name="connection"></param>
    public SQLiteConnection(SQLiteConnection connection)
      : this(connection.ConnectionString)
    {
      string str;

      if (connection.State == ConnectionState.Open)
      {
        Open();

        // Reattach all attached databases from the existing connection
        using (DataTable tbl = connection.GetSchema("Catalogs"))
        {
          foreach (DataRow row in tbl.Rows)
          {
            str = row[0].ToString();
            if (String.Compare(str, "main", StringComparison.OrdinalIgnoreCase) != 0
              && String.Compare(str, "temp", StringComparison.OrdinalIgnoreCase) != 0)
            {
              using (SQLiteCommand cmd = CreateCommand())
              {
                cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "ATTACH DATABASE '{0}' AS [{1}]", row[1], row[0]);
                cmd.ExecuteNonQuery();
              }
            }
          }
        }
      }
    }

#if PLATFORM_COMPACTFRAMEWORK
    /// <summary>
    /// Obsolete
    /// </summary>
    public override int ConnectionTimeout
    {
      get
      {
        return 30;
      }
    }
#endif

    /// <summary>
    /// Creates a clone of the connection.  All attached databases and user-defined functions are cloned.  If the existing connection is open, the cloned connection 
    /// will also be opened.
    /// </summary>
    /// <returns></returns>
    public object Clone()
    {
      return new SQLiteConnection(this);
    }

    /// <summary>
    /// Disposes of the SQLiteConnection, closing it if it is active.
    /// </summary>
    /// <param name="disposing">True if the connection is being explicitly closed.</param>
    protected override void Dispose(bool disposing)
    {
      base.Dispose(disposing);

      if (disposing)
        Close();
    }

    /// <summary>
    /// Creates a database file.  This just creates a zero-byte file which SQLite
    /// will turn into a database when the file is opened properly.
    /// </summary>
    /// <param name="databaseFileName">The file to create</param>
    static public void CreateFile(string databaseFileName)
    {
      FileStream fs = File.Create(databaseFileName);
      fs.Close();
    }

    /// <summary>
    /// Raises the state change event when the state of the connection changes
    /// </summary>
    /// <param name="newState">The new state.  If it is different from the previous state, an event is raised.</param>
    internal void OnStateChange(ConnectionState newState)
    {
      ConnectionState oldState = _connectionState;
      _connectionState = newState;

      if (StateChange != null && oldState != newState)
      {
        StateChangeEventArgs e = new StateChangeEventArgs(oldState, newState);
        StateChange(this, e);
      }
    }

    /// <summary>
    /// OBSOLETE.  Creates a new SQLiteTransaction if one isn't already active on the connection.
    /// </summary>
    /// <param name="isolationLevel">This parameter is ignored.</param>
    /// <param name="deferredLock">When TRUE, SQLite defers obtaining a write lock until a write operation is requested.
    /// When FALSE, a writelock is obtained immediately.  The default is TRUE, but in a multi-threaded multi-writer 
    /// environment, one may instead choose to lock the database immediately to avoid any possible writer deadlock.</param>
    /// <returns>Returns a SQLiteTransaction object.</returns>
    [Obsolete("Use one of the standard BeginTransaction methods, this one will be removed soon")]
    public SQLiteTransaction BeginTransaction(IsolationLevel isolationLevel, bool deferredLock)
    {
      return (SQLiteTransaction)BeginDbTransaction(deferredLock == false ? IsolationLevel.Serializable : IsolationLevel.ReadCommitted);
    }

    /// <summary>
    /// OBSOLETE.  Creates a new SQLiteTransaction if one isn't already active on the connection.
    /// </summary>
    /// <param name="deferredLock">When TRUE, SQLite defers obtaining a write lock until a write operation is requested.
    /// When FALSE, a writelock is obtained immediately.  The default is false, but in a multi-threaded multi-writer 
    /// environment, one may instead choose to lock the database immediately to avoid any possible writer deadlock.</param>
    /// <returns>Returns a SQLiteTransaction object.</returns>
    [Obsolete("Use one of the standard BeginTransaction methods, this one will be removed soon")]
    public SQLiteTransaction BeginTransaction(bool deferredLock)
    {
      return (SQLiteTransaction)BeginDbTransaction(deferredLock == false ? IsolationLevel.Serializable : IsolationLevel.ReadCommitted);
    }

    /// <summary>
    /// Creates a new SQLiteTransaction if one isn't already active on the connection.
    /// </summary>
    /// <param name="isolationLevel">Supported isolation levels are Serializable, ReadCommitted and Unspecified.</param>
    /// <remarks>
    /// Unspecified will use the default isolation level specified in the connection string.  If no isolation level is specified in the 
    /// connection string, Serializable is used.
    /// Serializable transactions are the default.  In this mode, the engine gets an immediate lock on the database, and no other threads
    /// may begin a transaction.  Other threads may read from the database, but not write.
    /// With a ReadCommitted isolation level, locks are deferred and elevated as needed.  It is possible for multiple threads to start
    /// a transaction in ReadCommitted mode, but if a thread attempts to commit a transaction while another thread
    /// has a ReadCommitted lock, it may timeout or cause a deadlock on both threads until both threads' CommandTimeout's are reached.
    /// </remarks>
    /// <returns>Returns a SQLiteTransaction object.</returns>
    public new SQLiteTransaction BeginTransaction(IsolationLevel isolationLevel)
    {
      return (SQLiteTransaction)BeginDbTransaction(isolationLevel);
    }

    /// <summary>
    /// Creates a new SQLiteTransaction if one isn't already active on the connection.
    /// </summary>
    /// <returns>Returns a SQLiteTransaction object.</returns>
    public new SQLiteTransaction BeginTransaction()
    {
      return (SQLiteTransaction)BeginDbTransaction(_defaultIsolation);
    }

    /// <summary>
    /// Forwards to the local BeginTransaction() function
    /// </summary>
    /// <param name="isolationLevel">Supported isolation levels are Unspecified, Serializable, and ReadCommitted</param>
    /// <returns></returns>
    protected override DbTransaction BeginDbTransaction(IsolationLevel isolationLevel)
    {
      if (_connectionState != ConnectionState.Open)
        throw new InvalidOperationException();

      if (isolationLevel == IsolationLevel.Unspecified) isolationLevel = _defaultIsolation;

      if (isolationLevel != IsolationLevel.Serializable && isolationLevel != IsolationLevel.ReadCommitted)
        throw new ArgumentException("isolationLevel");

      return new SQLiteTransaction(this, isolationLevel != IsolationLevel.Serializable);
    }

    /// <summary>
    /// Not implemented
    /// </summary>
    /// <param name="databaseName"></param>
    public override void ChangeDatabase(string databaseName)
    {
      throw new NotImplementedException();
    }

    /// <summary>
    /// When the database connection is closed, all commands linked to this connection are automatically reset.
    /// </summary>
    public override void Close()
    {
      if (_sql != null)
      {
#if !PLATFORM_COMPACTFRAMEWORK
        if (_enlistment != null)
        {
          // If the connection is enlisted in a transaction scope and the scope is still active,
          // we cannot truly shut down this connection until the scope has completed.  Therefore make a 
          // hidden connection temporarily to hold open the connection until the scope has completed.
          SQLiteConnection cnn = new SQLiteConnection();
          cnn._sql = _sql;
          cnn._transactionLevel = _transactionLevel;
          cnn._enlistment = _enlistment;
          cnn._connectionState = _connectionState;
          cnn._version = _version;

          cnn._enlistment._transaction._cnn = cnn;
          cnn._enlistment._disposeConnection = true;
          _sql = null;
          _enlistment = null;
        }
#endif
        if (_sql != null)
        {
          _sql.Close();
        }
        _sql = null;
        _transactionLevel = 0;
      }
      OnStateChange(ConnectionState.Closed);
    }

    /// <summary>
    /// Clears the connection pool associated with the connection.  Any other active connections using the same database file
    /// will be discarded instead of returned to the pool when they are closed.
    /// </summary>
    /// <param name="connection"></param>
    public static void ClearPool(SQLiteConnection connection)
    {
      if (connection._sql == null) return;
      connection._sql.ClearPool();
    }

    /// <summary>
    /// Clears all connection pools.  Any active connections will be discarded instead of sent to the pool when they are closed.
    /// </summary>
    public static void ClearAllPools()
    {
      SQLiteConnectionPool.ClearAllPools();
    }

    /// <summary>
    /// The connection string containing the parameters for the connection
    /// </summary>
    /// <remarks>
    /// <list type="table">
    /// <listheader>
    /// <term>Parameter</term>
    /// <term>Values</term>
    /// <term>Required</term>
    /// <term>Default</term>
    /// </listheader>
    /// <item>
    /// <description>Data Source</description>
    /// <description>{filename}</description>
    /// <description>Y</description>
    /// <description></description>
    /// </item>
    /// <item>
    /// <description>Version</description>
    /// <description>3</description>
    /// <description>N</description>
    /// <description>3</description>
    /// </item>
    /// <item>
    /// <description>UseUTF16Encoding</description>
    /// <description><b>True</b><br/><b>False</b></description>
    /// <description>N</description>
    /// <description>False</description>
    /// </item>
    /// <item>
    /// <description>DateTimeFormat</description>
    /// <description><b>Ticks</b> - Use DateTime.Ticks<br/><b>ISO8601</b> - Use ISO8601 DateTime format<br/><b>JulianDay</b> - Use JulianDay format</description>
    /// <description>N</description>
    /// <description>ISO8601</description>
    /// </item>
    /// <item>
    /// <description>BinaryGUID</description>
    /// <description><b>Yes/On/1</b> - Store GUID columns in binary form<br/><b>No/Off/0</b> - Store GUID columns as text</description>
    /// <description>N</description>
    /// <description>On</description>
    /// </item>
    /// <item>
    /// <description>Cache Size</description>
    /// <description>{size in bytes}</description>
    /// <description>N</description>
    /// <description>2000</description>
    /// </item>
    /// <item>
    /// <description>Synchronous</description>
    /// <description><b>Normal</b> - Normal file flushing behavior<br/><b>Full</b> - Full flushing after all writes<br/><b>Off</b> - Underlying OS flushes I/O's</description>
    /// <description>N</description>
    /// <description>Normal</description>
    /// </item>
    /// <item>
    /// <description>Page Size</description>
    /// <description>{size in bytes}</description>
    /// <description>N</description>
    /// <description>1024</description>
    /// </item>
    /// <item>
    /// <description>Password</description>
    /// <description>{password}</description>
    /// <description>N</description>
    /// <description></description>
    /// </item>
    /// <item>
    /// <description>Enlist</description>
    /// <description><B>Y</B> - Automatically enlist in distributed transactions<br/><b>N</b> - No automatic enlistment</description>
    /// <description>N</description>
    /// <description>Y</description>
    /// </item>
    /// <item>
    /// <description>Pooling</description>
    /// <description><b>True</b> - Use connection pooling<br/><b>False</b> - Do not use connection pooling</description>
    /// <description>N</description>
    /// <description>False</description>
    /// </item>
    /// <item>
    /// <description>FailIfMissing</description>
    /// <description><b>True</b> - Don't create the database if it does not exist, throw an error instead<br/><b>False</b> - Automatically create the database if it does not exist</description>
    /// <description>N</description>
    /// <description>False</description>
    /// </item>
    /// <item>
    /// <description>Max Page Count</description>
    /// <description>{size in pages} - Limits the maximum number of pages (limits the size) of the database</description>
    /// <description>N</description>
    /// <description>0</description>
    /// </item>
    /// <item>
    /// <description>Legacy Format</description>
    /// <description><b>True</b> - Use the more compatible legacy 3.x database format<br/><b>False</b> - Use the newer 3.3x database format which compresses numbers more effectively</description>
    /// <description>N</description>
    /// <description>False</description>
    /// </item>
    /// <item>
    /// <description>Default Timeout</description>
    /// <description>{time in seconds}<br/>The default command timeout</description>
    /// <description>N</description>
    /// <description>30</description>
    /// </item>
    /// <item>
    /// <description>Journal Mode</description>
    /// <description><b>Delete</b> - Delete the journal file after a commit<br/><b>Persist</b> - Zero out and leave the journal file on disk after a commit<br/><b>Off</b> - Disable the rollback journal entirely</description>
    /// <description>N</description>
    /// <description>Delete</description>
    /// </item>
    /// <item>
    /// <description>Read Only</description>
    /// <description><b>True</b> - Open the database for read only access<br/><b>False</b> - Open the database for normal read/write access</description>
    /// <description>N</description>
    /// <description>False</description>
    /// </item>
    /// <item>
    /// <description>Max Pool Size</description>
    /// <description>The maximum number of connections for the given connection string that can be in the connection pool</description>
    /// <description>N</description>
    /// <description>100</description>
    /// </item>
    /// <item>
    /// <description>Default IsolationLevel</description>
    /// <description>The default transaciton isolation level</description>
    /// <description>N</description>
    /// <description>Serializable</description>
    /// </item>
    /// </list>
    /// </remarks>
#if !PLATFORM_COMPACTFRAMEWORK
    [RefreshProperties(RefreshProperties.All), DefaultValue("")]
	[Editor("SQLite.Designer.SQLiteConnectionStringEditor, SQLite.Designer, Version=1.0.38.1, Culture=neutral, PublicKeyToken=db937bc2d44ff139", "System.Drawing.Design.UITypeEditor, System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a")]
#endif
    public override string ConnectionString
    {
      get
      {
        return _connectionString;
      }
      set
      {
        if (value == null)
          throw new ArgumentNullException();

        else if (_connectionState != ConnectionState.Closed)
          throw new InvalidOperationException();

        _connectionString = value;
      }
    }

    /// <summary>
    /// Create a new SQLiteCommand and associate it with this connection.
    /// </summary>
    /// <returns>Returns an instantiated SQLiteCommand object already assigned to this connection.</returns>
    public new SQLiteCommand CreateCommand()
    {
      return new SQLiteCommand(this);
    }

    /// <summary>
    /// Forwards to the local CreateCommand() function
    /// </summary>
    /// <returns></returns>
    protected override DbCommand CreateDbCommand()
    {
      return CreateCommand();
    }

    /// <summary>
    /// Returns the filename without extension or path
    /// </summary>
#if !PLATFORM_COMPACTFRAMEWORK
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
#endif
    public override string DataSource
    {
      get
      {
        return _dataSource;
      }
    }

    /// <summary>
    /// Returns an empty string
    /// </summary>
#if !PLATFORM_COMPACTFRAMEWORK
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
#endif
    public override string Database
    {
      get
      {
        return "main";
      }
    }

    internal static string MapUriPath(string path)
    {
	    if (path.StartsWith ("file://", StringComparison.OrdinalIgnoreCase))
		    return path.Substring (7);
      else if (path.StartsWith ("file:", StringComparison.OrdinalIgnoreCase))
		    return path.Substring (5);
      else if (path.StartsWith ("/", StringComparison.OrdinalIgnoreCase))
		    return path;
      else
		    throw new InvalidOperationException ("Invalid connection string: invalid URI");
    }
    
    /// <summary>
    /// Parses the connection string into component parts
    /// </summary>
    /// <param name="connectionString">The connection string to parse</param>
    /// <returns>An array of key-value pairs representing each parameter of the connection string</returns>
    internal static SortedList<string, string> ParseConnectionString(string connectionString)
    {
      string s = connectionString;
      int n;
      SortedList<string, string> ls = new SortedList<string, string>(StringComparer.OrdinalIgnoreCase);

      // First split into semi-colon delimited values.  The Split() function of SQLiteBase accounts for and properly
      // skips semi-colons in quoted strings
      string[] arParts = SQLiteConvert.Split(s, ';');
      string[] arPiece;

      int x = arParts.Length;
      // For each semi-colon piece, split into key and value pairs by the presence of the = sign
      for (n = 0; n < x; n++)
      {
        arPiece = SQLiteConvert.Split(arParts[n], '=');
        if (arPiece.Length == 2)
        {
          ls.Add(arPiece[0], arPiece[1]);
        }
        else throw new ArgumentException(String.Format(CultureInfo.CurrentCulture, "Invalid ConnectionString format for parameter \"{0}\"", (arPiece.Length > 0) ? arPiece[0] : "null"));
      }
      return ls;
    }

#if !PLATFORM_COMPACTFRAMEWORK
    /// <summary>
    /// Manual distributed transaction enlistment support
    /// </summary>
    /// <param name="transaction">The distributed transaction to enlist in</param>
    public override void EnlistTransaction(System.Transactions.Transaction transaction)
    {
      if (_transactionLevel > 0 && transaction != null)
        throw new ArgumentException("Unable to enlist in transaction, a local transaction already exists");

      if (_enlistment != null && transaction == _enlistment._scope)
        return;
      else if (_enlistment != null)
        throw new ArgumentException("Already enlisted in a transaction");

      _enlistment = new SQLiteEnlistment(this, transaction);
    }
#endif

    /// <summary>
    /// Looks for a key in the array of key/values of the parameter string.  If not found, return the specified default value
    /// </summary>
    /// <param name="items">The list to look in</param>
    /// <param name="key">The key to find</param>
    /// <param name="defValue">The default value to return if the key is not found</param>
    /// <returns>The value corresponding to the specified key, or the default value if not found.</returns>
    static internal string FindKey(SortedList<string, string> items, string key, string defValue)
    {
      string ret;

      if (items.TryGetValue(key, out ret)) return ret;

      return defValue;
    }

    /// <summary>
    /// Opens the connection using the parameters found in the <see cref="ConnectionString">ConnectionString</see>
    /// </summary>
    public override void Open()
    {
      if (_connectionState != ConnectionState.Closed)
        throw new InvalidOperationException();

      Close();

      SortedList<string, string> opts = ParseConnectionString(_connectionString);
      string fileName;

      if (Convert.ToInt32(FindKey(opts, "Version", "3"), CultureInfo.InvariantCulture) != 3)
        throw new NotSupportedException("Only SQLite Version 3 is supported at this time");

      fileName = FindKey(opts, "Data Source", "");

      if (String.IsNullOrEmpty(fileName))
      {
        fileName = FindKey(opts, "Uri", "");
        if (String.IsNullOrEmpty(fileName))
          throw new ArgumentException("Data Source cannot be empty.  Use :memory: to open an in-memory database");
        else
          fileName = MapUriPath(fileName);
      }

      if (String.Compare(fileName, ":MEMORY:", StringComparison.OrdinalIgnoreCase) == 0)
        fileName = ":memory:";
      else
      {
#if PLATFORM_COMPACTFRAMEWORK
       if (fileName.StartsWith(".\\"))
         fileName = Path.GetDirectoryName(System.Reflection.Assembly.GetCallingAssembly().GetName().CodeBase) + fileName.Substring(1);
#endif
       fileName = ExpandFileName(fileName);
      }
      try
      {
        bool usePooling = (SQLiteConvert.ToBoolean(FindKey(opts, "Pooling", Boolean.FalseString)) == true);
        bool bUTF16 = (SQLiteConvert.ToBoolean(FindKey(opts, "UseUTF16Encoding", Boolean.FalseString)) == true);
        int maxPoolSize = Convert.ToInt32(FindKey(opts, "Max Pool Size", "100"), CultureInfo.InvariantCulture);

        _defaultTimeout = Convert.ToInt32(FindKey(opts, "Default Timeout", "30"), CultureInfo.CurrentCulture);

        _defaultIsolation = (IsolationLevel)Enum.Parse(typeof(IsolationLevel), FindKey(opts, "Default IsolationLevel", "Serializable"), true);
        if (_defaultIsolation != IsolationLevel.Serializable && _defaultIsolation != IsolationLevel.ReadCommitted)
          throw new NotSupportedException("Invalid Default IsolationLevel specified");

        SQLiteDateFormats dateFormat = (SQLiteDateFormats)Enum.Parse(typeof(SQLiteDateFormats), FindKey(opts, "DateTimeFormat", "ISO8601"), true);
        //string temp = FindKey(opts, "DateTimeFormat", "ISO8601");
        //if (String.Compare(temp, "ticks", StringComparison.OrdinalIgnoreCase) == 0) dateFormat = SQLiteDateFormats.Ticks;
        //else if (String.Compare(temp, "julianday", StringComparison.OrdinalIgnoreCase) == 0) dateFormat = SQLiteDateFormats.JulianDay;

        if (bUTF16) // SQLite automatically sets the encoding of the database to UTF16 if called from sqlite3_open16()
          _sql = new SQLite3_UTF16(dateFormat);
        else
          _sql = new SQLite3(dateFormat);

        SQLiteOpenFlagsEnum flags = SQLiteOpenFlagsEnum.None;

        if (SQLiteConvert.ToBoolean(FindKey(opts, "FailIfMissing", Boolean.FalseString)) == false)
          flags |= SQLiteOpenFlagsEnum.Create;

        if (SQLiteConvert.ToBoolean(FindKey(opts, "Read Only", Boolean.FalseString)) == true)
        {
          flags |= SQLiteOpenFlagsEnum.ReadOnly;
          // SQLite will return SQLITE_MISUSE on ReadOnly and Create
          flags &= ~SQLiteOpenFlagsEnum.Create;
        }
        else
        {
          flags |= SQLiteOpenFlagsEnum.ReadWrite;
        }

        _sql.Open(fileName, flags, maxPoolSize, usePooling);

        _binaryGuid = (SQLiteConvert.ToBoolean(FindKey(opts, "BinaryGUID", Boolean.TrueString)) == true);

        string password = FindKey(opts, "Password", null);

        if (String.IsNullOrEmpty(password) == false)
          _sql.SetPassword(System.Text.UTF8Encoding.UTF8.GetBytes(password));
        else if (_password != null)
          _sql.SetPassword(_password);
        _password = null;

        _dataSource = Path.GetFileNameWithoutExtension(fileName);

        _version++;

        ConnectionState oldstate = _connectionState;
        _connectionState = ConnectionState.Open;
        try
        {
          using (SQLiteCommand cmd = CreateCommand())
          {
            string defValue;

            if (fileName != ":memory:")
            {
              defValue = FindKey(opts, "Page Size", "1024");
              if (Convert.ToInt32(defValue, CultureInfo.InvariantCulture) != 1024)
              {
                cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA page_size={0}", defValue);
                cmd.ExecuteNonQuery();
              }
            }

            defValue = FindKey(opts, "Max Page Count", "0");
            if (Convert.ToInt32(defValue, CultureInfo.InvariantCulture) != 0)
            {
              cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA max_page_count={0}", defValue);
              cmd.ExecuteNonQuery();
            }

            defValue = FindKey(opts, "Legacy Format", Boolean.FalseString);
            cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA legacy_file_format={0}", SQLiteConvert.ToBoolean(defValue) == true ? "ON" : "OFF");
            cmd.ExecuteNonQuery();

            defValue = FindKey(opts, "Synchronous", "Normal");
            if (String.Compare(defValue, "Full", StringComparison.OrdinalIgnoreCase) != 0)
            {
              cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA synchronous={0}", defValue);
              cmd.ExecuteNonQuery();
            }

            defValue = FindKey(opts, "Cache Size", "2000");
            if (Convert.ToInt32(defValue, CultureInfo.InvariantCulture) != 2000)
            {
              cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA cache_size={0}", defValue);
              cmd.ExecuteNonQuery();
            }

            defValue = FindKey(opts, "Journal Mode", "Delete");
            if (String.Compare(defValue, "Default", StringComparison.OrdinalIgnoreCase) != 0)
            {
              cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA journal_mode={0}", defValue);
              cmd.ExecuteNonQuery();
            }

            defValue = FindKey(opts, "Foreign Keys", Boolean.FalseString);
            cmd.CommandText = String.Format(CultureInfo.InvariantCulture, "PRAGMA foreign_keys={0}", SQLiteConvert.ToBoolean(defValue) == true ? "ON" : "OFF");
            cmd.ExecuteNonQuery();
          }

          if (_commitHandler != null)
            _sql.SetCommitHook(_commitCallback);

          if (_updateHandler != null)
            _sql.SetUpdateHook(_updateCallback);

          if (_rollbackHandler != null)
            _sql.SetRollbackHook(_rollbackCallback);

#if !PLATFORM_COMPACTFRAMEWORK
          if (Transactions.Transaction.Current != null && SQLiteConvert.ToBoolean(FindKey(opts, "Enlist", Boolean.TrueString)) == true)
            EnlistTransaction(Transactions.Transaction.Current);
#endif

          _connectionState = oldstate;
          OnStateChange(ConnectionState.Open);
        }
        catch
        {
          _connectionState = oldstate;
          throw;
        }
      }
      catch (SQLiteException)
      {
        Close();
        throw;
      }
    }

    /// <summary>
    /// Gets/sets the default command timeout for newly-created commands.  This is especially useful for 
    /// commands used internally such as inside a SQLiteTransaction, where setting the timeout is not possible.
    /// This can also be set in the ConnectionString with "Default Timeout"
    /// </summary>
    public int DefaultTimeout
    {
      get { return _defaultTimeout; }
      set { _defaultTimeout = value; }
    }

    /// <summary>
    /// Returns the version of the underlying SQLite database engine
    /// </summary>
#if !PLATFORM_COMPACTFRAMEWORK
    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
#endif
    public override string ServerVersion
    {
      get
      {
        return SQLiteVersion;
        //if (_connectionState != ConnectionState.Open)
        //  throw new InvalidOperationException();

        //return _sql.Version;
      }
    }

    /// <summary>
    /// Returns the version of the underlying SQLite database engine
    /// </summary>
    public static string SQLiteVersion
    {
      get { return SQLite3.SQLiteVersion; }
    }

    /// <summary>
    /// Returns the state of the connection.
    /// </summary>
#if !PLATFORM_COMPACTFRAMEWORK
    [Browsable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
#endif
    public override ConnectionState State
    {
      get
      {
        return _connectionState;
      }
    }

    /// <summary>
    /// Change the password (or assign a password) to an open database.
    /// </summary>
    /// <remarks>
    /// No readers or writers may be active for this process.  The database must already be open
    /// and if it already was password protected, the existing password must already have been supplied.
    /// </remarks>
    /// <param name="newPassword">The new password to assign to the database</param>
    public void ChangePassword(string newPassword)
    {
      ChangePassword(String.IsNullOrEmpty(newPassword) ? null : System.Text.UTF8Encoding.UTF8.GetBytes(newPassword));
    }

    /// <summary>
    /// Change the password (or assign a password) to an open database.
    /// </summary>
    /// <remarks>
    /// No readers or writers may be active for this process.  The database must already be open
    /// and if it already was password protected, the existing password must already have been supplied.
    /// </remarks>
    /// <param name="newPassword">The new password to assign to the database</param>
    public void ChangePassword(byte[] newPassword)
    {
      if (_connectionState != ConnectionState.Open)
        throw new InvalidOperationException("Database must be opened before changing the password.");

      _sql.ChangePassword(newPassword);
    }

    /// <summary>
    /// Sets the password for a password-protected database.  A password-protected database is
    /// unusable for any operation until the password has been set.
    /// </summary>
    /// <param name="databasePassword">The password for the database</param>
    public void SetPassword(string databasePassword)
    {
      SetPassword(String.IsNullOrEmpty(databasePassword) ? null : System.Text.UTF8Encoding.UTF8.GetBytes(databasePassword));
    }

    /// <summary>
    /// Sets the password for a password-protected database.  A password-protected database is
    /// unusable for any operation until the password has been set.
    /// </summary>
    /// <param name="databasePassword">The password for the database</param>
    public void SetPassword(byte[] databasePassword)
    {
      if (_connectionState != ConnectionState.Closed)
        throw new InvalidOperationException("Password can only be set before the database is opened.");

      if (databasePassword != null)
        if (databasePassword.Length == 0) databasePassword = null;

      _password = databasePassword;
    }

    /// <summary>
    /// Expand the filename of the data source, resolving the |DataDirectory| macro as appropriate.
    /// </summary>
    /// <param name="sourceFile">The database filename to expand</param>
    /// <returns>The expanded path and filename of the filename</returns>
    private string ExpandFileName(string sourceFile)
    {
      if (String.IsNullOrEmpty(sourceFile)) return sourceFile;

      if (sourceFile.StartsWith(_dataDirectory, StringComparison.OrdinalIgnoreCase))
      {
        string dataDirectory;

#if PLATFORM_COMPACTFRAMEWORK
        dataDirectory = Path.GetDirectoryName(System.Reflection.Assembly.GetCallingAssembly().GetName().CodeBase);
#else
        dataDirectory = AppDomain.CurrentDomain.GetData("DataDirectory") as string;
        if (String.IsNullOrEmpty(dataDirectory))
          dataDirectory = AppDomain.CurrentDomain.BaseDirectory;
#endif

        if (sourceFile.Length > _dataDirectory.Length)
        {
          if (sourceFile[_dataDirectory.Length] == Path.DirectorySeparatorChar ||
              sourceFile[_dataDirectory.Length] == Path.AltDirectorySeparatorChar)
            sourceFile = sourceFile.Remove(_dataDirectory.Length, 1);
        }
        sourceFile = Path.Combine(dataDirectory, sourceFile.Substring(_dataDirectory.Length));
      }

#if !PLATFORM_COMPACTFRAMEWORK
      sourceFile = Path.GetFullPath(sourceFile);
#endif

      return sourceFile;
    }

    ///<overloads>
    /// The following commands are used to extract schema information out of the database.  Valid schema types are:
    /// <list type="bullet">
    /// <item>
    /// <description>MetaDataCollections</description>
    /// </item>
    /// <item>
    /// <description>DataSourceInformation</description>
    /// </item>
    /// <item>
    /// <description>Catalogs</description>
    /// </item>
    /// <item>
    /// <description>Columns</description>
    /// </item>
    /// <item>
    /// <description>ForeignKeys</description>
    /// </item>
    /// <item>
    /// <description>Indexes</description>
    /// </item>
    /// <item>
    /// <description>IndexColumns</description>
    /// </item>
    /// <item>
    /// <description>Tables</description>
    /// </item>
    /// <item>
    /// <description>Views</description>
    /// </item>
    /// <item>
    /// <description>ViewColumns</description>
    /// </item>
    /// </list>
    /// </overloads>
    /// <summary>
    /// Returns the MetaDataCollections schema
    /// </summary>
    /// <returns>A DataTable of the MetaDataCollections schema</returns>
    public override DataTable GetSchema()
    {
      return GetSchema("MetaDataCollections", null);
    }

    /// <summary>
    /// Returns schema information of the specified collection
    /// </summary>
    /// <param name="collectionName">The schema collection to retrieve</param>
    /// <returns>A DataTable of the specified collection</returns>
    public override DataTable GetSchema(string collectionName)
    {
      return GetSchema(collectionName, new string[0]);
    }

    /// <summary>
    /// Retrieves schema information using the specified constraint(s) for the specified collection
    /// </summary>
    /// <param name="collectionName">The collection to retrieve</param>
    /// <param name="restrictionValues">The restrictions to impose</param>
    /// <returns>A DataTable of the specified collection</returns>
    public override DataTable GetSchema(string collectionName, string[] restrictionValues)
    {
      if (_connectionState != ConnectionState.Open)
        throw new InvalidOperationException();

      string[] parms = new string[5];

      if (restrictionValues == null) restrictionValues = new string[0];
      restrictionValues.CopyTo(parms, 0);

      switch (collectionName.ToUpper(CultureInfo.InvariantCulture))
      {
        case "METADATACOLLECTIONS":
          return Schema_MetaDataCollections();
        case "DATASOURCEINFORMATION":
          return Schema_DataSourceInformation();
        case "DATATYPES":
          return Schema_DataTypes();
        case "COLUMNS":
        case "TABLECOLUMNS":
          return Schema_Columns(parms[0], parms[2], parms[3]);
        case "INDEXES":
          return Schema_Indexes(parms[0], parms[2], parms[3]);
        case "TRIGGERS":
          return Schema_Triggers(parms[0], parms[2], parms[3]);
        case "INDEXCOLUMNS":
          return Schema_IndexColumns(parms[0], parms[2], parms[3], parms[4]);
        case "TABLES":
          return Schema_Tables(parms[0], parms[2], parms[3]);
        case "VIEWS":
          return Schema_Views(parms[0], parms[2]);
        case "VIEWCOLUMNS":
          return Schema_ViewColumns(parms[0], parms[2], parms[3]);
        case "FOREIGNKEYS":
          return Schema_ForeignKeys(parms[0], parms[2], parms[3]);
        case "CATALOGS":
          return Schema_Catalogs(parms[0]);
        case "RESERVEDWORDS":
          return Schema_ReservedWords();
      }
      throw new NotSupportedException();
    }

    private static DataTable Schema_ReservedWords()
    {
      DataTable tbl = new DataTable("MetaDataCollections");

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("ReservedWord", typeof(string));
      tbl.Columns.Add("MaximumVersion", typeof(string));
      tbl.Columns.Add("MinimumVersion", typeof(string));

      tbl.BeginLoadData();
      DataRow row;
      foreach (string word in SR.Keywords.Split(new char[] { ',' }))
      {
        row = tbl.NewRow();
        row[0] = word;
        tbl.Rows.Add(row);
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Builds a MetaDataCollections schema datatable
    /// </summary>
    /// <returns>DataTable</returns>
    private static DataTable Schema_MetaDataCollections()
    {
      DataTable tbl = new DataTable("MetaDataCollections");

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("CollectionName", typeof(string));
      tbl.Columns.Add("NumberOfRestrictions", typeof(int));
      tbl.Columns.Add("NumberOfIdentifierParts", typeof(int));

      tbl.BeginLoadData();

      StringReader reader = new StringReader(SR.MetaDataCollections);
      tbl.ReadXml(reader);
      reader.Close();

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Builds a DataSourceInformation datatable
    /// </summary>
    /// <returns>DataTable</returns>
    private DataTable Schema_DataSourceInformation()
    {
      DataTable tbl = new DataTable("DataSourceInformation");
      DataRow row;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add(DbMetaDataColumnNames.CompositeIdentifierSeparatorPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.DataSourceProductName, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.DataSourceProductVersion, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.DataSourceProductVersionNormalized, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.GroupByBehavior, typeof(int));
      tbl.Columns.Add(DbMetaDataColumnNames.IdentifierPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.IdentifierCase, typeof(int));
      tbl.Columns.Add(DbMetaDataColumnNames.OrderByColumnsInSelect, typeof(bool));
      tbl.Columns.Add(DbMetaDataColumnNames.ParameterMarkerFormat, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.ParameterMarkerPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.ParameterNameMaxLength, typeof(int));
      tbl.Columns.Add(DbMetaDataColumnNames.ParameterNamePattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.QuotedIdentifierPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.QuotedIdentifierCase, typeof(int));
      tbl.Columns.Add(DbMetaDataColumnNames.StatementSeparatorPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.StringLiteralPattern, typeof(string));
      tbl.Columns.Add(DbMetaDataColumnNames.SupportedJoinOperators, typeof(int));

      tbl.BeginLoadData();

      row = tbl.NewRow();
      row.ItemArray = new object[] {
        null,
        "SQLite",
        _sql.Version,
        _sql.Version,
        3,
        @"(^\[\p{Lo}\p{Lu}\p{Ll}_@#][\p{Lo}\p{Lu}\p{Ll}\p{Nd}@$#_]*$)|(^\[[^\]\0]|\]\]+\]$)|(^\""[^\""\0]|\""\""+\""$)",
        1,
        false,
        "{0}",
        @"@[\p{Lo}\p{Lu}\p{Ll}\p{Lm}_@#][\p{Lo}\p{Lu}\p{Ll}\p{Lm}\p{Nd}\uff3f_@#\$]*(?=\s+|$)",
        255,
        @"^[\p{Lo}\p{Lu}\p{Ll}\p{Lm}_@#][\p{Lo}\p{Lu}\p{Ll}\p{Lm}\p{Nd}\uff3f_@#\$]*(?=\s+|$)",
        @"(([^\[]|\]\])*)",
        1,
        ";",
        @"'(([^']|'')*)'",
        15
      };
      tbl.Rows.Add(row);

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Build a Columns schema
    /// </summary>
    /// <param name="strCatalog">The catalog (attached database) to query, can be null</param>
    /// <param name="strTable">The table to retrieve schema information for, must not be null</param>
    /// <param name="strColumn">The column to retrieve schema information for, can be null</param>
    /// <returns>DataTable</returns>
    private DataTable Schema_Columns(string strCatalog, string strTable, string strColumn)
    {
      DataTable tbl = new DataTable("Columns");
      DataRow row;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("COLUMN_NAME", typeof(string));
      tbl.Columns.Add("COLUMN_GUID", typeof(Guid));
      tbl.Columns.Add("COLUMN_PROPID", typeof(long));
      tbl.Columns.Add("ORDINAL_POSITION", typeof(int));
      tbl.Columns.Add("COLUMN_HASDEFAULT", typeof(bool));
      tbl.Columns.Add("COLUMN_DEFAULT", typeof(string));
      tbl.Columns.Add("COLUMN_FLAGS", typeof(long));
      tbl.Columns.Add("IS_NULLABLE", typeof(bool));
      tbl.Columns.Add("DATA_TYPE", typeof(string));
      tbl.Columns.Add("TYPE_GUID", typeof(Guid));
      tbl.Columns.Add("CHARACTER_MAXIMUM_LENGTH", typeof(int));
      tbl.Columns.Add("CHARACTER_OCTET_LENGTH", typeof(int));
      tbl.Columns.Add("NUMERIC_PRECISION", typeof(int));
      tbl.Columns.Add("NUMERIC_SCALE", typeof(int));
      tbl.Columns.Add("DATETIME_PRECISION", typeof(long));
      tbl.Columns.Add("CHARACTER_SET_CATALOG", typeof(string));
      tbl.Columns.Add("CHARACTER_SET_SCHEMA", typeof(string));
      tbl.Columns.Add("CHARACTER_SET_NAME", typeof(string));
      tbl.Columns.Add("COLLATION_CATALOG", typeof(string));
      tbl.Columns.Add("COLLATION_SCHEMA", typeof(string));
      tbl.Columns.Add("COLLATION_NAME", typeof(string));
      tbl.Columns.Add("DOMAIN_CATALOG", typeof(string));
      tbl.Columns.Add("DOMAIN_NAME", typeof(string));
      tbl.Columns.Add("DESCRIPTION", typeof(string));
      tbl.Columns.Add("PRIMARY_KEY", typeof(bool));
      tbl.Columns.Add("EDM_TYPE", typeof(string));
      tbl.Columns.Add("AUTOINCREMENT", typeof(bool));
      tbl.Columns.Add("UNIQUE", typeof(bool));

      tbl.BeginLoadData();

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      using (SQLiteCommand cmdTables = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'table' OR [type] LIKE 'view'", strCatalog, master), this))
      using (SQLiteDataReader rdTables = cmdTables.ExecuteReader())
      {
        while (rdTables.Read())
        {
          if (String.IsNullOrEmpty(strTable) || String.Compare(strTable, rdTables.GetString(2), StringComparison.OrdinalIgnoreCase) == 0)
          {
            try
            {
              using (SQLiteCommand cmd = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}]", strCatalog, rdTables.GetString(2)), this))
              using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader(CommandBehavior.SchemaOnly))
              using (DataTable tblSchema = rd.GetSchemaTable(true, true))
              {
                foreach (DataRow schemaRow in tblSchema.Rows)
                {
                  if (String.Compare(schemaRow[SchemaTableColumn.ColumnName].ToString(), strColumn, StringComparison.OrdinalIgnoreCase) == 0
                    || strColumn == null)
                  {
                    row = tbl.NewRow();

                    row["NUMERIC_PRECISION"] = schemaRow[SchemaTableColumn.NumericPrecision];
                    row["NUMERIC_SCALE"] = schemaRow[SchemaTableColumn.NumericScale];
                    row["TABLE_NAME"] = rdTables.GetString(2);
                    row["COLUMN_NAME"] = schemaRow[SchemaTableColumn.ColumnName];
                    row["TABLE_CATALOG"] = strCatalog;
                    row["ORDINAL_POSITION"] = schemaRow[SchemaTableColumn.ColumnOrdinal];
                    row["COLUMN_HASDEFAULT"] = (schemaRow[SchemaTableOptionalColumn.DefaultValue] != DBNull.Value);
                    row["COLUMN_DEFAULT"] = schemaRow[SchemaTableOptionalColumn.DefaultValue];
                    row["IS_NULLABLE"] = schemaRow[SchemaTableColumn.AllowDBNull];
                    row["DATA_TYPE"] = schemaRow["DataTypeName"].ToString().ToLower(CultureInfo.InvariantCulture);
                    row["EDM_TYPE"] = SQLiteConvert.DbTypeToTypeName((DbType)schemaRow[SchemaTableColumn.ProviderType]).ToString().ToLower(CultureInfo.InvariantCulture);
                    row["CHARACTER_MAXIMUM_LENGTH"] = schemaRow[SchemaTableColumn.ColumnSize];
                    row["TABLE_SCHEMA"] = schemaRow[SchemaTableColumn.BaseSchemaName];
                    row["PRIMARY_KEY"] = schemaRow[SchemaTableColumn.IsKey];
                    row["AUTOINCREMENT"] = schemaRow[SchemaTableOptionalColumn.IsAutoIncrement];
                    row["COLLATION_NAME"] = schemaRow["CollationType"];
                    row["UNIQUE"] = schemaRow[SchemaTableColumn.IsUnique];
                    tbl.Rows.Add(row);
                  }
                }
              }
            }
            catch(SQLiteException)
            {
            }
          }
        }
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Returns index information for the given database and catalog
    /// </summary>
    /// <param name="strCatalog">The catalog (attached database) to query, can be null</param>
    /// <param name="strIndex">The name of the index to retrieve information for, can be null</param>
    /// <param name="strTable">The table to retrieve index information for, can be null</param>
    /// <returns>DataTable</returns>
    private DataTable Schema_Indexes(string strCatalog, string strTable, string strIndex)
    {
      DataTable tbl = new DataTable("Indexes");
      DataRow row;
      List<int> primaryKeys = new List<int>();
      bool maybeRowId;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("INDEX_CATALOG", typeof(string));
      tbl.Columns.Add("INDEX_SCHEMA", typeof(string));
      tbl.Columns.Add("INDEX_NAME", typeof(string));
      tbl.Columns.Add("PRIMARY_KEY", typeof(bool));
      tbl.Columns.Add("UNIQUE", typeof(bool));
      tbl.Columns.Add("CLUSTERED", typeof(bool));
      tbl.Columns.Add("TYPE", typeof(int));
      tbl.Columns.Add("FILL_FACTOR", typeof(int));
      tbl.Columns.Add("INITIAL_SIZE", typeof(int));
      tbl.Columns.Add("NULLS", typeof(int));
      tbl.Columns.Add("SORT_BOOKMARKS", typeof(bool));
      tbl.Columns.Add("AUTO_UPDATE", typeof(bool));
      tbl.Columns.Add("NULL_COLLATION", typeof(int));
      tbl.Columns.Add("ORDINAL_POSITION", typeof(int));
      tbl.Columns.Add("COLUMN_NAME", typeof(string));
      tbl.Columns.Add("COLUMN_GUID", typeof(Guid));
      tbl.Columns.Add("COLUMN_PROPID", typeof(long));
      tbl.Columns.Add("COLLATION", typeof(short));
      tbl.Columns.Add("CARDINALITY", typeof(Decimal));
      tbl.Columns.Add("PAGES", typeof(int));
      tbl.Columns.Add("FILTER_CONDITION", typeof(string));
      tbl.Columns.Add("INTEGRATED", typeof(bool));
      tbl.Columns.Add("INDEX_DEFINITION", typeof(string));

      tbl.BeginLoadData();

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;
      
      using (SQLiteCommand cmdTables = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'table'", strCatalog, master), this))
      using (SQLiteDataReader rdTables = cmdTables.ExecuteReader())
      {
        while (rdTables.Read())
        {
          maybeRowId = false;
          primaryKeys.Clear();
          if (String.IsNullOrEmpty(strTable) || String.Compare(rdTables.GetString(2), strTable, StringComparison.OrdinalIgnoreCase) == 0)
          {
            // First, look for any rowid indexes -- which sqlite defines are INTEGER PRIMARY KEY columns.
            // Such indexes are not listed in the indexes list but count as indexes just the same.
            try
            {
              using (SQLiteCommand cmdTable = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].table_info([{1}])", strCatalog, rdTables.GetString(2)), this))
              using (SQLiteDataReader rdTable = cmdTable.ExecuteReader())
              {
                while (rdTable.Read())
                {
                  if (rdTable.GetInt32(5) == 1)
                  {
                    primaryKeys.Add(rdTable.GetInt32(0));

                    // If the primary key is of type INTEGER, then its a rowid and we need to make a fake index entry for it.
                    if (String.Compare(rdTable.GetString(2), "INTEGER", StringComparison.OrdinalIgnoreCase) == 0)
                      maybeRowId = true;
                  }
                }
              }
            }
            catch (SQLiteException)
            {
            }
            if (primaryKeys.Count == 1 && maybeRowId == true)
            {
              row = tbl.NewRow();

              row["TABLE_CATALOG"] = strCatalog;
              row["TABLE_NAME"] = rdTables.GetString(2);
              row["INDEX_CATALOG"] = strCatalog;
              row["PRIMARY_KEY"] = true;
              row["INDEX_NAME"] = String.Format(CultureInfo.InvariantCulture, "{1}_PK_{0}", rdTables.GetString(2), master);
              row["UNIQUE"] = true;

              if (String.Compare((string)row["INDEX_NAME"], strIndex, StringComparison.OrdinalIgnoreCase) == 0
              || strIndex == null)
              {
                tbl.Rows.Add(row);
              }

              primaryKeys.Clear();
            }

            // Now fetch all the rest of the indexes.
            try
            {
              using (SQLiteCommand cmd = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].index_list([{1}])", strCatalog, rdTables.GetString(2)), this))
              using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader())
              {
                while (rd.Read())
                {
                  if (String.Compare(rd.GetString(1), strIndex, StringComparison.OrdinalIgnoreCase) == 0
                  || strIndex == null)
                  {
                    row = tbl.NewRow();

                    row["TABLE_CATALOG"] = strCatalog;
                    row["TABLE_NAME"] = rdTables.GetString(2);
                    row["INDEX_CATALOG"] = strCatalog;
                    row["INDEX_NAME"] = rd.GetString(1);
                    row["UNIQUE"] = rd.GetBoolean(2);
                    row["PRIMARY_KEY"] = false;

                    // get the index definition
                    using (SQLiteCommand cmdIndexes = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{2}] WHERE [type] LIKE 'index' AND [name] LIKE '{1}'", strCatalog, rd.GetString(1).Replace("'", "''"), master), this))
                    using (SQLiteDataReader rdIndexes = cmdIndexes.ExecuteReader())
                    {
                      while (rdIndexes.Read())
                      {
                        if (rdIndexes.IsDBNull(4) == false)
                          row["INDEX_DEFINITION"] = rdIndexes.GetString(4);
                        break;
                      }
                    }

                    // Now for the really hard work.  Figure out which index is the primary key index.
                    // The only way to figure it out is to check if the index was an autoindex and if we have a non-rowid
                    // primary key, and all the columns in the given index match the primary key columns
                    if (primaryKeys.Count > 0 && rd.GetString(1).StartsWith("sqlite_autoindex_" + rdTables.GetString(2), StringComparison.InvariantCultureIgnoreCase) == true)
                    {
                      using (SQLiteCommand cmdDetails = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].index_info([{1}])", strCatalog, rd.GetString(1)), this))
                      using (SQLiteDataReader rdDetails = cmdDetails.ExecuteReader())
                      {
                        int nMatches = 0;
                        while (rdDetails.Read())
                        {
                          if (primaryKeys.Contains(rdDetails.GetInt32(1)) == false)
                          {
                            nMatches = 0;
                            break;
                          }
                          nMatches++;
                        }
                        if (nMatches == primaryKeys.Count)
                        {
                          row["PRIMARY_KEY"] = true;
                          primaryKeys.Clear();
                        }
                      }
                    }

                    tbl.Rows.Add(row);
                  }
                }
              }
            }
            catch (SQLiteException)
            {
            }
          }
        }
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    private DataTable Schema_Triggers(string catalog, string table, string triggerName)
    {
      DataTable tbl = new DataTable("Triggers");
      DataRow row;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("TRIGGER_NAME", typeof(string));
      tbl.Columns.Add("TRIGGER_DEFINITION", typeof(string));

      tbl.BeginLoadData();

      if (String.IsNullOrEmpty(table)) table = null;
      if (String.IsNullOrEmpty(catalog)) catalog = "main";
      string master = (String.Compare(catalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      using (SQLiteCommand cmd = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT [type], [name], [tbl_name], [rootpage], [sql], [rowid] FROM [{0}].[{1}] WHERE [type] LIKE 'trigger'", catalog, master), this))
      using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader())
      {
        while (rd.Read())
        {
          if (String.Compare(rd.GetString(1), triggerName, StringComparison.OrdinalIgnoreCase) == 0
            || triggerName == null)
          {
            if (table == null || String.Compare(table, rd.GetString(2), StringComparison.OrdinalIgnoreCase) == 0)
            {
              row = tbl.NewRow();

              row["TABLE_CATALOG"] = catalog;
              row["TABLE_NAME"] = rd.GetString(2);
              row["TRIGGER_NAME"] = rd.GetString(1);
              row["TRIGGER_DEFINITION"] = rd.GetString(4);

              tbl.Rows.Add(row);
            }
          }
        }
      }
      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Retrieves table schema information for the database and catalog
    /// </summary>
    /// <param name="strCatalog">The catalog (attached database) to retrieve tables on</param>
    /// <param name="strTable">The table to retrieve, can be null</param>
    /// <param name="strType">The table type, can be null</param>
    /// <returns>DataTable</returns>
    private DataTable Schema_Tables(string strCatalog, string strTable, string strType)
    {
      DataTable tbl = new DataTable("Tables");
      DataRow row;
      string strItem;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("TABLE_TYPE", typeof(string));
      tbl.Columns.Add("TABLE_ID", typeof(long));
      tbl.Columns.Add("TABLE_ROOTPAGE", typeof(int));
      tbl.Columns.Add("TABLE_DEFINITION", typeof(string));
      tbl.BeginLoadData();

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      using (SQLiteCommand cmd = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT [type], [name], [tbl_name], [rootpage], [sql], [rowid] FROM [{0}].[{1}] WHERE [type] LIKE 'table'", strCatalog, master), this))
      using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader())
      {
        while (rd.Read())
        {
          strItem = rd.GetString(0);
          if (String.Compare(rd.GetString(2), 0, "SQLITE_", 0, 7, StringComparison.OrdinalIgnoreCase) == 0)
            strItem = "SYSTEM_TABLE";

          if (String.Compare(strType, strItem, StringComparison.OrdinalIgnoreCase) == 0
            || strType == null)
          {
            if (String.Compare(rd.GetString(2), strTable, StringComparison.OrdinalIgnoreCase) == 0
              || strTable == null)
            {
              row = tbl.NewRow();

              row["TABLE_CATALOG"] = strCatalog;
              row["TABLE_NAME"] = rd.GetString(2);
              row["TABLE_TYPE"] = strItem;
              row["TABLE_ID"] = rd.GetInt64(5);
              row["TABLE_ROOTPAGE"] = rd.GetInt32(3);
              row["TABLE_DEFINITION"] = rd.GetString(4);

              tbl.Rows.Add(row);
            }
          }
        }
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Retrieves view schema information for the database
    /// </summary>
    /// <param name="strCatalog">The catalog (attached database) to retrieve views on</param>
    /// <param name="strView">The view name, can be null</param>
    /// <returns>DataTable</returns>
    private DataTable Schema_Views(string strCatalog, string strView)
    {
      DataTable tbl = new DataTable("Views");
      DataRow row;
      string strItem;
      int nPos;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("VIEW_DEFINITION", typeof(string));
      tbl.Columns.Add("CHECK_OPTION", typeof(bool));
      tbl.Columns.Add("IS_UPDATABLE", typeof(bool));
      tbl.Columns.Add("DESCRIPTION", typeof(string));
      tbl.Columns.Add("DATE_CREATED", typeof(DateTime));
      tbl.Columns.Add("DATE_MODIFIED", typeof(DateTime));

      tbl.BeginLoadData();

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      using (SQLiteCommand cmd = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'view'", strCatalog, master), this))
      using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader())
      {
        while (rd.Read())
        {
          if (String.Compare(rd.GetString(1), strView, StringComparison.OrdinalIgnoreCase) == 0
            || String.IsNullOrEmpty(strView))
          {
            strItem = rd.GetString(4).Replace('\r', ' ').Replace('\n', ' ').Replace('\t', ' ');
            nPos = CultureInfo.InvariantCulture.CompareInfo.IndexOf(strItem, " AS ", CompareOptions.IgnoreCase);
            if (nPos > -1)
            {
              strItem = strItem.Substring(nPos + 4).Trim();
              row = tbl.NewRow();

              row["TABLE_CATALOG"] = strCatalog;
              row["TABLE_NAME"] = rd.GetString(2);
              row["IS_UPDATABLE"] = false;
              row["VIEW_DEFINITION"] = strItem;

              tbl.Rows.Add(row);
            }
          }
        }
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Retrieves catalog (attached databases) schema information for the database
    /// </summary>
    /// <param name="strCatalog">The catalog to retrieve, can be null</param>
    /// <returns>DataTable</returns>
    private DataTable Schema_Catalogs(string strCatalog)
    {
      DataTable tbl = new DataTable("Catalogs");
      DataRow row;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("CATALOG_NAME", typeof(string));
      tbl.Columns.Add("DESCRIPTION", typeof(string));
      tbl.Columns.Add("ID", typeof(long));

      tbl.BeginLoadData();

      using (SQLiteCommand cmd = new SQLiteCommand("PRAGMA database_list", this))
      using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader())
      {
        while (rd.Read())
        {
          if (String.Compare(rd.GetString(1), strCatalog, StringComparison.OrdinalIgnoreCase) == 0
            || strCatalog == null)
          {
            row = tbl.NewRow();

            row["CATALOG_NAME"] = rd.GetString(1);
            row["DESCRIPTION"] = rd.GetString(2);
            row["ID"] = rd.GetInt64(0);

            tbl.Rows.Add(row);
          }
        }
      }

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    private DataTable Schema_DataTypes()
    {
      DataTable tbl = new DataTable("DataTypes");

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("TypeName", typeof(String));
      tbl.Columns.Add("ProviderDbType", typeof(int));
      tbl.Columns.Add("ColumnSize", typeof(long));
      tbl.Columns.Add("CreateFormat", typeof(String));
      tbl.Columns.Add("CreateParameters", typeof(String));
      tbl.Columns.Add("DataType", typeof(String));
      tbl.Columns.Add("IsAutoIncrementable", typeof(bool));
      tbl.Columns.Add("IsBestMatch", typeof(bool));
      tbl.Columns.Add("IsCaseSensitive", typeof(bool));
      tbl.Columns.Add("IsFixedLength", typeof(bool));
      tbl.Columns.Add("IsFixedPrecisionScale", typeof(bool));
      tbl.Columns.Add("IsLong", typeof(bool));
      tbl.Columns.Add("IsNullable", typeof(bool));
      tbl.Columns.Add("IsSearchable", typeof(bool));
      tbl.Columns.Add("IsSearchableWithLike", typeof(bool));
      tbl.Columns.Add("IsLiteralSupported", typeof(bool));
      tbl.Columns.Add("LiteralPrefix", typeof(String));
      tbl.Columns.Add("LiteralSuffix", typeof(String));
      tbl.Columns.Add("IsUnsigned", typeof(bool));
      tbl.Columns.Add("MaximumScale", typeof(short));
      tbl.Columns.Add("MinimumScale", typeof(short));
      tbl.Columns.Add("IsConcurrencyType", typeof(bool));

      tbl.BeginLoadData();

      StringReader reader = new StringReader(SR.DataTypes);
      tbl.ReadXml(reader);
      reader.Close();

      tbl.AcceptChanges();
      tbl.EndLoadData();

      return tbl;
    }

    /// <summary>
    /// Returns the base column information for indexes in a database
    /// </summary>
    /// <param name="strCatalog">The catalog to retrieve indexes for (can be null)</param>
    /// <param name="strTable">The table to restrict index information by (can be null)</param>
    /// <param name="strIndex">The index to restrict index information by (can be null)</param>
    /// <param name="strColumn">The source column to restrict index information by (can be null)</param>
    /// <returns>A DataTable containing the results</returns>
    private DataTable Schema_IndexColumns(string strCatalog, string strTable, string strIndex, string strColumn)
    {
      DataTable tbl = new DataTable("IndexColumns");
      DataRow row;
      List<KeyValuePair<int, string>> primaryKeys = new List<KeyValuePair<int, string>>();
      bool maybeRowId;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("CONSTRAINT_CATALOG", typeof(string));
      tbl.Columns.Add("CONSTRAINT_SCHEMA", typeof(string));
      tbl.Columns.Add("CONSTRAINT_NAME", typeof(string));
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("COLUMN_NAME", typeof(string));
      tbl.Columns.Add("ORDINAL_POSITION", typeof(int));
      tbl.Columns.Add("INDEX_NAME", typeof(string));
      tbl.Columns.Add("COLLATION_NAME", typeof(string));
      tbl.Columns.Add("SORT_MODE", typeof(string));
      tbl.Columns.Add("CONFLICT_OPTION", typeof(int));

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      tbl.BeginLoadData();

      using (SQLiteCommand cmdTables = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'table'", strCatalog, master), this))
      using (SQLiteDataReader rdTables = cmdTables.ExecuteReader())
      {
        while (rdTables.Read())
        {
          maybeRowId = false;
          primaryKeys.Clear();
          if (String.IsNullOrEmpty(strTable) || String.Compare(rdTables.GetString(2), strTable, StringComparison.OrdinalIgnoreCase) == 0)
          {
            try
            {
              using (SQLiteCommand cmdTable = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].table_info([{1}])", strCatalog, rdTables.GetString(2)), this))
              using (SQLiteDataReader rdTable = cmdTable.ExecuteReader())
              {
                while (rdTable.Read())
                {
                  if (rdTable.GetInt32(5) == 1) // is a primary key
                  {
                    primaryKeys.Add(new KeyValuePair<int, string>(rdTable.GetInt32(0), rdTable.GetString(1)));
                    // Is an integer -- could be a rowid if no other primary keys exist in the table
                    if (String.Compare(rdTable.GetString(2), "INTEGER", StringComparison.OrdinalIgnoreCase) == 0)
                      maybeRowId = true;
                  }
                }
              }
            }
            catch (SQLiteException)
            {
            }
            // This is a rowid row
            if (primaryKeys.Count == 1 && maybeRowId == true)
            {
              row = tbl.NewRow();
              row["CONSTRAINT_CATALOG"] = strCatalog;
              row["CONSTRAINT_NAME"] = String.Format(CultureInfo.InvariantCulture, "{1}_PK_{0}", rdTables.GetString(2), master);
              row["TABLE_CATALOG"] = strCatalog;
              row["TABLE_NAME"] = rdTables.GetString(2);
              row["COLUMN_NAME"] = primaryKeys[0].Value;
              row["INDEX_NAME"] = row["CONSTRAINT_NAME"];
              row["ORDINAL_POSITION"] = 0; // primaryKeys[0].Key;
              row["COLLATION_NAME"] = "BINARY";
              row["SORT_MODE"] = "ASC";
              row["CONFLICT_OPTION"] = 2;

              if (String.IsNullOrEmpty(strIndex) || String.Compare(strIndex, (string)row["INDEX_NAME"], StringComparison.OrdinalIgnoreCase) == 0)
                tbl.Rows.Add(row);
            }

            using (SQLiteCommand cmdIndexes = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{2}] WHERE [type] LIKE 'index' AND [tbl_name] LIKE '{1}'", strCatalog, rdTables.GetString(2).Replace("'", "''"), master), this))
            using (SQLiteDataReader rdIndexes = cmdIndexes.ExecuteReader())
            {
              while (rdIndexes.Read())
              {
                int ordinal = 0;
                if (String.IsNullOrEmpty(strIndex) || String.Compare(strIndex, rdIndexes.GetString(1), StringComparison.OrdinalIgnoreCase) == 0)
                {
                  try
                  {
                    using (SQLiteCommand cmdIndex = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].index_info([{1}])", strCatalog, rdIndexes.GetString(1)), this))
                    using (SQLiteDataReader rdIndex = cmdIndex.ExecuteReader())
                    {
                      while (rdIndex.Read())
                      {
                        row = tbl.NewRow();
                        row["CONSTRAINT_CATALOG"] = strCatalog;
                        row["CONSTRAINT_NAME"] = rdIndexes.GetString(1);
                        row["TABLE_CATALOG"] = strCatalog;
                        row["TABLE_NAME"] = rdIndexes.GetString(2);
                        row["COLUMN_NAME"] = rdIndex.GetString(2);
                        row["INDEX_NAME"] = rdIndexes.GetString(1);
                        row["ORDINAL_POSITION"] = ordinal; // rdIndex.GetInt32(1);

                        string collationSequence;
                        int sortMode;
                        int onError;
                        _sql.GetIndexColumnExtendedInfo(strCatalog, rdIndexes.GetString(1), rdIndex.GetString(2), out sortMode, out onError, out collationSequence);

                        if (String.IsNullOrEmpty(collationSequence) == false)
                          row["COLLATION_NAME"] = collationSequence;

                        row["SORT_MODE"] = (sortMode == 0) ? "ASC" : "DESC";
                        row["CONFLICT_OPTION"] = onError;

                        ordinal++;

                        if (String.IsNullOrEmpty(strColumn) || String.Compare(strColumn, row["COLUMN_NAME"].ToString(), StringComparison.OrdinalIgnoreCase) == 0)
                          tbl.Rows.Add(row);
                      }
                    }
                  }
                  catch (SQLiteException)
                  {
                  }
                }
              }
            }
          }
        }
      }

      tbl.EndLoadData();
      tbl.AcceptChanges();

      return tbl;
    }

    /// <summary>
    /// Returns detailed column information for a specified view
    /// </summary>
    /// <param name="strCatalog">The catalog to retrieve columns for (can be null)</param>
    /// <param name="strView">The view to restrict column information by (can be null)</param>
    /// <param name="strColumn">The source column to restrict column information by (can be null)</param>
    /// <returns>A DataTable containing the results</returns>
    private DataTable Schema_ViewColumns(string strCatalog, string strView, string strColumn)
    {
      DataTable tbl = new DataTable("ViewColumns");
      DataRow row;
      string strSql;
      int n;
      DataRow schemaRow;
      DataRow viewRow;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("VIEW_CATALOG", typeof(string));
      tbl.Columns.Add("VIEW_SCHEMA", typeof(string));
      tbl.Columns.Add("VIEW_NAME", typeof(string));
      tbl.Columns.Add("VIEW_COLUMN_NAME", typeof(String));
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("COLUMN_NAME", typeof(string));
      tbl.Columns.Add("ORDINAL_POSITION", typeof(int));
      tbl.Columns.Add("COLUMN_HASDEFAULT", typeof(bool));
      tbl.Columns.Add("COLUMN_DEFAULT", typeof(string));
      tbl.Columns.Add("COLUMN_FLAGS", typeof(long));
      tbl.Columns.Add("IS_NULLABLE", typeof(bool));
      tbl.Columns.Add("DATA_TYPE", typeof(string));
      tbl.Columns.Add("CHARACTER_MAXIMUM_LENGTH", typeof(int));
      tbl.Columns.Add("NUMERIC_PRECISION", typeof(int));
      tbl.Columns.Add("NUMERIC_SCALE", typeof(int));
      tbl.Columns.Add("DATETIME_PRECISION", typeof(long));
      tbl.Columns.Add("CHARACTER_SET_CATALOG", typeof(string));
      tbl.Columns.Add("CHARACTER_SET_SCHEMA", typeof(string));
      tbl.Columns.Add("CHARACTER_SET_NAME", typeof(string));
      tbl.Columns.Add("COLLATION_CATALOG", typeof(string));
      tbl.Columns.Add("COLLATION_SCHEMA", typeof(string));
      tbl.Columns.Add("COLLATION_NAME", typeof(string));
      tbl.Columns.Add("PRIMARY_KEY", typeof(bool));
      tbl.Columns.Add("EDM_TYPE", typeof(string));
      tbl.Columns.Add("AUTOINCREMENT", typeof(bool));
      tbl.Columns.Add("UNIQUE", typeof(bool));

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;
      
      tbl.BeginLoadData();

      using (SQLiteCommand cmdViews = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'view'", strCatalog, master), this))
      using (SQLiteDataReader rdViews = cmdViews.ExecuteReader())
      {
        while (rdViews.Read())
        {
          if (String.IsNullOrEmpty(strView) || String.Compare(strView, rdViews.GetString(2), StringComparison.OrdinalIgnoreCase) == 0)
          {
            using (SQLiteCommand cmdViewSelect = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}]", strCatalog, rdViews.GetString(2)), this))
            {
              strSql = rdViews.GetString(4).Replace('\r', ' ').Replace('\n', ' ').Replace('\t', ' ');
              n = CultureInfo.InvariantCulture.CompareInfo.IndexOf(strSql, " AS ", CompareOptions.IgnoreCase);
              if (n < 0)
                continue;

              strSql = strSql.Substring(n + 4);

              using (SQLiteCommand cmd = new SQLiteCommand(strSql, this))
              using (SQLiteDataReader rdViewSelect = cmdViewSelect.ExecuteReader(CommandBehavior.SchemaOnly))
              using (SQLiteDataReader rd = (SQLiteDataReader)cmd.ExecuteReader(CommandBehavior.SchemaOnly))
              using (DataTable tblSchemaView = rdViewSelect.GetSchemaTable(false, false))
              using (DataTable tblSchema = rd.GetSchemaTable(false, false))
              {
                for (n = 0; n < tblSchema.Rows.Count; n++)
                {
                  viewRow = tblSchemaView.Rows[n];
                  schemaRow = tblSchema.Rows[n];

                  if (String.Compare(viewRow[SchemaTableColumn.ColumnName].ToString(), strColumn, StringComparison.OrdinalIgnoreCase) == 0
                    || strColumn == null)
                  {
                    row = tbl.NewRow();

                    row["VIEW_CATALOG"] = strCatalog;
                    row["VIEW_NAME"] = rdViews.GetString(2);
                    row["TABLE_CATALOG"] = strCatalog;
                    row["TABLE_SCHEMA"] = schemaRow[SchemaTableColumn.BaseSchemaName];
                    row["TABLE_NAME"] = schemaRow[SchemaTableColumn.BaseTableName];
                    row["COLUMN_NAME"] = schemaRow[SchemaTableColumn.BaseColumnName];
                    row["VIEW_COLUMN_NAME"] = viewRow[SchemaTableColumn.ColumnName];
                    row["COLUMN_HASDEFAULT"] = (viewRow[SchemaTableOptionalColumn.DefaultValue] != DBNull.Value);
                    row["COLUMN_DEFAULT"] = viewRow[SchemaTableOptionalColumn.DefaultValue];
                    row["ORDINAL_POSITION"] = viewRow[SchemaTableColumn.ColumnOrdinal];
                    row["IS_NULLABLE"] = viewRow[SchemaTableColumn.AllowDBNull];
                    row["DATA_TYPE"] = viewRow["DataTypeName"]; // SQLiteConvert.DbTypeToType((DbType)viewRow[SchemaTableColumn.ProviderType]).ToString();
                    row["EDM_TYPE"] = SQLiteConvert.DbTypeToTypeName((DbType)viewRow[SchemaTableColumn.ProviderType]).ToString().ToLower(CultureInfo.InvariantCulture);
                    row["CHARACTER_MAXIMUM_LENGTH"] = viewRow[SchemaTableColumn.ColumnSize];
                    row["TABLE_SCHEMA"] = viewRow[SchemaTableColumn.BaseSchemaName];
                    row["PRIMARY_KEY"] = viewRow[SchemaTableColumn.IsKey];
                    row["AUTOINCREMENT"] = viewRow[SchemaTableOptionalColumn.IsAutoIncrement];
                    row["COLLATION_NAME"] = viewRow["CollationType"];
                    row["UNIQUE"] = viewRow[SchemaTableColumn.IsUnique];
                    tbl.Rows.Add(row);
                  }
                }
              }
            }
          }
        }
      }

      tbl.EndLoadData();
      tbl.AcceptChanges();

      return tbl;
    }

    /// <summary>
    /// Retrieves foreign key information from the specified set of filters
    /// </summary>
    /// <param name="strCatalog">An optional catalog to restrict results on</param>
    /// <param name="strTable">An optional table to restrict results on</param>
    /// <param name="strKeyName">An optional foreign key name to restrict results on</param>
    /// <returns>A DataTable with the results of the query</returns>
    private DataTable Schema_ForeignKeys(string strCatalog, string strTable, string strKeyName)
    {
      DataTable tbl = new DataTable("ForeignKeys");
      DataRow row;

      tbl.Locale = CultureInfo.InvariantCulture;
      tbl.Columns.Add("CONSTRAINT_CATALOG", typeof(string));
      tbl.Columns.Add("CONSTRAINT_SCHEMA", typeof(string));
      tbl.Columns.Add("CONSTRAINT_NAME", typeof(string));
      tbl.Columns.Add("TABLE_CATALOG", typeof(string));
      tbl.Columns.Add("TABLE_SCHEMA", typeof(string));
      tbl.Columns.Add("TABLE_NAME", typeof(string));
      tbl.Columns.Add("CONSTRAINT_TYPE", typeof(string));
      tbl.Columns.Add("IS_DEFERRABLE", typeof(bool));
      tbl.Columns.Add("INITIALLY_DEFERRED", typeof(bool));
      tbl.Columns.Add("FKEY_FROM_COLUMN", typeof(string));
      tbl.Columns.Add("FKEY_FROM_ORDINAL_POSITION", typeof(int));
      tbl.Columns.Add("FKEY_TO_CATALOG", typeof(string));
      tbl.Columns.Add("FKEY_TO_SCHEMA", typeof(string));
      tbl.Columns.Add("FKEY_TO_TABLE", typeof(string));
      tbl.Columns.Add("FKEY_TO_COLUMN", typeof(string));

      if (String.IsNullOrEmpty(strCatalog)) strCatalog = "main";

      string master = (String.Compare(strCatalog, "temp", StringComparison.OrdinalIgnoreCase) == 0) ? _tempmasterdb : _masterdb;

      tbl.BeginLoadData();

      using (SQLiteCommand cmdTables = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}] WHERE [type] LIKE 'table'", strCatalog, master), this))
      using (SQLiteDataReader rdTables = cmdTables.ExecuteReader())
      {
        while (rdTables.Read())
        {
          if (String.IsNullOrEmpty(strTable) || String.Compare(strTable, rdTables.GetString(2), StringComparison.OrdinalIgnoreCase) == 0)
          {
            try
            {
              using (SQLiteCommandBuilder builder = new SQLiteCommandBuilder())
              //using (SQLiteCommand cmdTable = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "SELECT * FROM [{0}].[{1}]", strCatalog, rdTables.GetString(2)), this))
              //using (SQLiteDataReader rdTable = cmdTable.ExecuteReader(CommandBehavior.SchemaOnly))
              using (SQLiteCommand cmdKey = new SQLiteCommand(String.Format(CultureInfo.InvariantCulture, "PRAGMA [{0}].foreign_key_list([{1}])", strCatalog, rdTables.GetString(2)), this))
              using (SQLiteDataReader rdKey = cmdKey.ExecuteReader())
              {
                while (rdKey.Read())
                {
                  row = tbl.NewRow();
                  row["CONSTRAINT_CATALOG"] = strCatalog;
                  row["CONSTRAINT_NAME"] = String.Format(CultureInfo.InvariantCulture, "FK_{0}_{1}", rdTables[2], rdKey.GetInt32(0));
                  row["TABLE_CATALOG"] = strCatalog;
                  row["TABLE_NAME"] = builder.UnquoteIdentifier(rdTables.GetString(2));
                  row["CONSTRAINT_TYPE"] = "FOREIGN KEY";
                  row["IS_DEFERRABLE"] = false;
                  row["INITIALLY_DEFERRED"] = false;
                  row["FKEY_FROM_COLUMN"] = builder.UnquoteIdentifier(rdKey[3].ToString());
                  row["FKEY_TO_CATALOG"] = strCatalog;
                  row["FKEY_TO_TABLE"] = builder.UnquoteIdentifier(rdKey[2].ToString());
                  row["FKEY_TO_COLUMN"] = builder.UnquoteIdentifier(rdKey[4].ToString());
                  row["FKEY_FROM_ORDINAL_POSITION"] = rdKey[1];

                  if (String.IsNullOrEmpty(strKeyName) || String.Compare(strKeyName, row["CONSTRAINT_NAME"].ToString(), StringComparison.OrdinalIgnoreCase) == 0)
                    tbl.Rows.Add(row);
                }
              }
            }
            catch (SQLiteException)
            {
            }
          }
        }
      }

      tbl.EndLoadData();
      tbl.AcceptChanges();

      return tbl;
    }

    /// <summary>
    /// This event is raised whenever SQLite makes an update/delete/insert into the database on
    /// this connection.  It only applies to the given connection.
    /// </summary>
    public event SQLiteUpdateEventHandler Update
    {
      add
      {
        if (_updateHandler == null)
        {
          _updateCallback = new SQLiteUpdateCallback(UpdateCallback);
          if (_sql != null) _sql.SetUpdateHook(_updateCallback);
        }
        _updateHandler += value;
      }
      remove
      {
        _updateHandler -= value;
        if (_updateHandler == null)
        {
          if (_sql != null) _sql.SetUpdateHook(null);
          _updateCallback = null;
        }
      }
    }

    private void UpdateCallback(IntPtr puser, int type, IntPtr database, IntPtr table, Int64 rowid)
    {
      _updateHandler(this, new UpdateEventArgs(
        SQLiteBase.UTF8ToString(database, -1),
        SQLiteBase.UTF8ToString(table, -1),
        (UpdateEventType)type,
        rowid));
    }

    /// <summary>
    /// This event is raised whenever SQLite is committing a transaction.
    /// Return non-zero to trigger a rollback
    /// </summary>
    public event SQLiteCommitHandler Commit
    {
      add
      {
        if (_commitHandler == null)
        {
          _commitCallback = new SQLiteCommitCallback(CommitCallback);
          if (_sql != null) _sql.SetCommitHook(_commitCallback);
        }
        _commitHandler += value;
      }
      remove
      {
        _commitHandler -= value;
        if (_commitHandler == null)
        {
          if (_sql != null) _sql.SetCommitHook(null);
          _commitCallback = null;
        }
      }
    }

    /// <summary>
    /// This event is raised whenever SQLite statement first begins executing on
    /// this connection.  It only applies to the given connection.
    /// </summary>
    public event SQLiteTraceEventHandler Trace
    {
      add
      {
        if (_traceHandler == null)
        {
          _traceCallback = new SQLiteTraceCallback(TraceCallback);
          if (_sql != null) _sql.SetTraceCallback(_traceCallback);
        }
        _traceHandler += value;
      }
      remove
      {
        _traceHandler -= value;
        if (_traceHandler == null)
        {
          if (_sql != null) _sql.SetTraceCallback(null);
            _traceCallback = null;
        }
      }
    }

    private void TraceCallback(IntPtr puser, IntPtr statement)
    {
      _traceHandler(this, new TraceEventArgs(
        SQLiteBase.UTF8ToString(statement, -1)));
    }

    /// <summary>
    /// This event is raised whenever SQLite is committing a transaction.
    /// Return non-zero to trigger a rollback
    /// </summary>
    public event EventHandler RollBack
    {
      add
      {
        if (_rollbackHandler == null)
        {
          _rollbackCallback = new SQLiteRollbackCallback(RollbackCallback);
          if (_sql != null) _sql.SetRollbackHook(_rollbackCallback);
        }
        _rollbackHandler += value;
      }
      remove
      {
        _rollbackHandler -= value;
        if (_rollbackHandler == null)
        {
          if (_sql != null) _sql.SetRollbackHook(null);
          _rollbackCallback = null;
        }
      }
    }


    private int CommitCallback(IntPtr parg)
    {
      CommitEventArgs e = new CommitEventArgs();
      _commitHandler(this, e);
      return (e.AbortTransaction == true) ? 1 : 0;
    }

    private void RollbackCallback(IntPtr parg)
    {
      _rollbackHandler(this, EventArgs.Empty);
    }
  }

  /// <summary>
  /// The I/O file cache flushing behavior for the connection
  /// </summary>
  public enum SynchronizationModes
  {
    /// <summary>
    /// Normal file flushing at critical sections of the code
    /// </summary>
    Normal = 0,
    /// <summary>
    /// Full file flushing after every write operation
    /// </summary>
    Full = 1,
    /// <summary>
    /// Use the default operating system's file flushing, SQLite does not explicitly flush the file buffers after writing
    /// </summary>
    Off = 2,
  }

#if !PLATFORM_COMPACTFRAMEWORK
  [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
  internal delegate void SQLiteUpdateCallback(IntPtr puser, int type, IntPtr database, IntPtr table, Int64 rowid);
#if !PLATFORM_COMPACTFRAMEWORK
  [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
  internal delegate int SQLiteCommitCallback(IntPtr puser);
#if !PLATFORM_COMPACTFRAMEWORK
  [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
  internal delegate void SQLiteTraceCallback(IntPtr puser, IntPtr statement);
#if !PLATFORM_COMPACTFRAMEWORK
  [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
#endif
  internal delegate void SQLiteRollbackCallback(IntPtr puser);

  /// <summary>
  /// Raised when a transaction is about to be committed.  To roll back a transaction, set the 
  /// rollbackTrans boolean value to true.
  /// </summary>
  /// <param name="sender">The connection committing the transaction</param>
  /// <param name="e">Event arguments on the transaction</param>
  public delegate void SQLiteCommitHandler(object sender, CommitEventArgs e);

  /// <summary>
  /// Raised when data is inserted, updated and deleted on a given connection
  /// </summary>
  /// <param name="sender">The connection committing the transaction</param>
  /// <param name="e">The event parameters which triggered the event</param>
  public delegate void SQLiteUpdateEventHandler(object sender, UpdateEventArgs e);

  /// <summary>
  /// Raised when a statement first begins executing on a given connection
  /// </summary>
  /// <param name="sender">The connection executing the statement</param>
  /// <param name="e">Event arguments on the trace</param>
  public delegate void SQLiteTraceEventHandler(object sender, TraceEventArgs e);

  /// <summary>
  /// Whenever an update event is triggered on a connection, this enum will indicate
  /// exactly what type of operation is being performed.
  /// </summary>
  public enum UpdateEventType
  {
    /// <summary>
    /// A row is being deleted from the given database and table
    /// </summary>
    Delete = 9,
    /// <summary>
    /// A row is being inserted into the table.
    /// </summary>
    Insert = 18,
    /// <summary>
    /// A row is being updated in the table.
    /// </summary>
    Update = 23,
  }

  /// <summary>
  /// Passed during an Update callback, these event arguments detail the type of update operation being performed
  /// on the given connection.
  /// </summary>
  public class UpdateEventArgs : EventArgs
  {
    /// <summary>
    /// The name of the database being updated (usually "main" but can be any attached or temporary database)
    /// </summary>
    public readonly string Database;

    /// <summary>
    /// The name of the table being updated
    /// </summary>
    public readonly string Table;

    /// <summary>
    /// The type of update being performed (insert/update/delete)
    /// </summary>
    public readonly UpdateEventType Event;

    /// <summary>
    /// The RowId affected by this update.
    /// </summary>
    public readonly Int64 RowId;

    internal UpdateEventArgs(string database, string table, UpdateEventType eventType, Int64 rowid)
    {
      Database = database;
      Table = table;
      Event = eventType;
      RowId = rowid;
    }
  }

  /// <summary>
  /// Event arguments raised when a transaction is being committed
  /// </summary>
  public class CommitEventArgs : EventArgs
  {
    internal CommitEventArgs()
    {
    }

    /// <summary>
    /// Set to true to abort the transaction and trigger a rollback
    /// </summary>
    public bool AbortTransaction;
  }

  /// <summary>
  /// Passed during an Trace callback, these event arguments contain the UTF-8 rendering of the SQL statement text
  /// </summary>
  public class TraceEventArgs : EventArgs
  {
    /// <summary>
    /// SQL statement text as the statement first begins executing
    /// </summary>
    public readonly string Statement;

    internal TraceEventArgs(string statement)
    {
      Statement = statement;
    }
  }

}
