System.Data.SQLite

    /// <summary>
    /// The connection the command is associated with
    /// </summary>
    private SQLiteConnection _cnn;
    /// <summary>
    /// The version of the connection the command is associated with
    /// </summary>
    private int _version;
    /// <summary>
    /// Indicates whether or not a DataReader is active on the command.
    /// </summary>
    private WeakReference _activeReader;
    /// <summary>
    /// The timeout for the command, kludged because SQLite doesn't support per-command timeout values
    /// </summary>

    /// Non-zero if the built-in (i.e. framework provided) connection string
    /// parser should be used when opening the connection.
    /// </summary>
    private bool _parseViaFramework;

    internal bool _binaryGuid;

    internal int _version;

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

    /// An array of rowid's for the active statement if CommandBehavior.KeyInfo is specified
    /// </summary>
    private SQLiteKeyReader _keyInfo;

    /// <summary>
    /// Matches the version of the connection.
    /// </summary>
    internal int _version;

    /// <summary>
    /// The "stub" (i.e. placeholder) base schema name to use when returning
    /// column schema information.  Matches the base schema name used by the
    /// associated connection.
    /// </summary>
    private string _baseSchemaName;

      if (_command == null)
        throw new InvalidOperationException("DataReader has been closed");

      if (_version == 0)
        throw new SQLiteException("Execution was aborted by the user");

      SQLiteConnection connection = _command.Connection;

      if (connection._version != _version || connection.State != ConnectionState.Open)
        throw new InvalidOperationException("Connection was closed, statement was terminated");
    }

    /// <summary>
    /// Throw an error if a row is not loaded
    /// </summary>
    private void CheckValidRow()

        {
            CheckDisposed();
            CheckClosed();

            return _stepCount;
        }
    }

    private int PrivateVisibleFieldCount
    {
        get { return _fieldCount; }
    }

    /// <summary>
    /// Returns the number of visible fields in the current resultset
    /// </summary>
    public override int VisibleFieldCount
    {
      get
      {
        CheckDisposed();
        CheckClosed();
        return PrivateVisibleFieldCount;
      }
    }

    /// <summary>
    /// This method is used to make sure the result set is open and a row is currently available.
    /// </summary>
    private void VerifyForGet()
    {
        CheckClosed();
        CheckValidRow();
    }

    /// <summary>
    /// SQLite is inherently un-typed.  All datatypes in SQLite are natively strings.  The definition of the columns of a table
    /// and the affinity of returned types are all we have to go on to type-restrict data in the reader.
    ///
    /// This function attempts to verify that the type of data being requested of a column matches the datatype of the column.  In
    /// the case of columns that are not backed into a table definition, we attempt to match up the affinity of a column (int, double, string or blob)
    /// to a set of known types that closely match that affinity.  It's not an exact science, but its the best we can do.
    /// </summary>
    /// <returns>
    /// This function throws an InvalidTypeCast() exception if the requested type doesn't match the column's definition or affinity.
    /// </returns>
    /// <param name="i">The index of the column to type-check</param>
    /// <param name="typ">The type we want to get out of the column</param>
    private TypeAffinity VerifyType(int i, DbType typ)
    {



        TypeAffinity affinity = GetSQLiteType(_flags, i).Affinity;

        switch (affinity)
        {
            case TypeAffinity.Int64:
                if (typ == DbType.Int64) return affinity;
                if (typ == DbType.Int32) return affinity;
                if (typ == DbType.Int16) return affinity;
                if (typ == DbType.Byte) return affinity;
                if (typ == DbType.SByte) return affinity;
                if (typ == DbType.Boolean) return affinity;
                if (typ == DbType.DateTime) return affinity;

                if (typ == DbType.Double) return affinity;
                if (typ == DbType.Single) return affinity;
                if (typ == DbType.Decimal) return affinity;
                break;
            case TypeAffinity.Double:

                if (typ == DbType.Double) return affinity;
                if (typ == DbType.Single) return affinity;
                if (typ == DbType.Decimal) return affinity;
                if (typ == DbType.DateTime) return affinity;
                break;
            case TypeAffinity.Text:
                if (typ == DbType.String) return affinity;
                if (typ == DbType.Guid) return affinity;
                if (typ == DbType.DateTime) return affinity;
                if (typ == DbType.Decimal) return affinity;
                break;
            case TypeAffinity.Blob:
                if (typ == DbType.Guid) return affinity;

                if (typ == DbType.Binary) return affinity;
                if (typ == DbType.String) return affinity;
                break;
        }

        throw new InvalidCastException();
    }

    /// <summary>
    /// Retrieves the column as a boolean value
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>bool</returns>
    public override bool GetBoolean(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetBoolean(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Boolean);
        return Convert.ToBoolean(GetValue(i), CultureInfo.CurrentCulture);
    }

    /// <summary>
    /// Retrieves the column as a single byte value
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>byte</returns>
    public override byte GetByte(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetByte(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Byte);
        return Convert.ToByte(_activeStatement._sql.GetInt32(_activeStatement, i));
    }

    /// <summary>
    /// Retrieves a column as an array of bytes (blob)
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <param name="fieldOffset">The zero-based index of where to begin reading the data</param>
    /// <param name="buffer">The buffer to write the bytes into</param>
    /// <param name="bufferoffset">The zero-based index of where to begin writing into the array</param>
    /// <param name="length">The number of bytes to retrieve</param>
    /// <returns>The actual number of bytes written into the array</returns>
    /// <remarks>
    /// To determine the number of bytes in the column, pass a null value for the buffer.  The total length will be returned.
    /// </remarks>
    public override long GetBytes(int i, long fieldOffset, byte[] buffer, int bufferoffset, int length)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetBytes(i - PrivateVisibleFieldCount, fieldOffset, buffer, bufferoffset, length);

        VerifyType(i, DbType.Binary);
        return _activeStatement._sql.GetBytes(_activeStatement, i, (int)fieldOffset, buffer, bufferoffset, length);
    }

    /// <summary>
    /// Returns the column as a single character
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>char</returns>
    public override char GetChar(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetChar(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.SByte);
        return Convert.ToChar(_activeStatement._sql.GetInt32(_activeStatement, i));
    }

    /// <summary>
    /// Retrieves a column as an array of chars (blob)
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <param name="fieldoffset">The zero-based index of where to begin reading the data</param>
    /// <param name="buffer">The buffer to write the characters into</param>
    /// <param name="bufferoffset">The zero-based index of where to begin writing into the array</param>
    /// <param name="length">The number of bytes to retrieve</param>
    /// <returns>The actual number of characters written into the array</returns>
    /// <remarks>
    /// To determine the number of characters in the column, pass a null value for the buffer.  The total length will be returned.
    /// </remarks>
    public override long GetChars(int i, long fieldoffset, char[] buffer, int bufferoffset, int length)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetChars(i - PrivateVisibleFieldCount, fieldoffset, buffer, bufferoffset, length);

        VerifyType(i, DbType.String);
        return _activeStatement._sql.GetChars(_activeStatement, i, (int)fieldoffset, buffer, bufferoffset, length);
    }

    /// <summary>
    /// Retrieves the name of the back-end datatype of the column
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>string</returns>
    public override string GetDataTypeName(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetDataTypeName(i - PrivateVisibleFieldCount);

        SQLiteType typ = GetSQLiteType(_flags, i);
        if (typ.Type == DbType.Object) return SQLiteConvert.SQLiteTypeToType(typ).Name;
        return _activeStatement._sql.ColumnType(_activeStatement, i, out typ.Affinity);
    }

    /// <summary>
    /// Retrieve the column as a date/time value
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>DateTime</returns>
    public override DateTime GetDateTime(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetDateTime(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.DateTime);
        return _activeStatement._sql.GetDateTime(_activeStatement, i);
    }

    /// <summary>
    /// Retrieve the column as a decimal value
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>decimal</returns>
    public override decimal GetDecimal(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetDecimal(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Decimal);
        return Decimal.Parse(_activeStatement._sql.GetText(_activeStatement, i), NumberStyles.AllowDecimalPoint | NumberStyles.AllowExponent | NumberStyles.AllowLeadingSign, CultureInfo.InvariantCulture);
    }

    /// <summary>
    /// Returns the column as a double
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>double</returns>
    public override double GetDouble(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetDouble(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Double);
        return _activeStatement._sql.GetDouble(_activeStatement, i);
    }

    /// <summary>
    /// Returns the .NET type of a given column
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>Type</returns>
    public override Type GetFieldType(int i)
    {
        CheckDisposed();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetFieldType(i - PrivateVisibleFieldCount);

        return SQLiteConvert.SQLiteTypeToType(GetSQLiteType(_flags, i));
    }

    /// <summary>
    /// Returns a column as a float value
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>float</returns>
    public override float GetFloat(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetFloat(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Single);
        return Convert.ToSingle(_activeStatement._sql.GetDouble(_activeStatement, i));
    }

    /// <summary>
    /// Returns the column as a Guid
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>Guid</returns>
    public override Guid GetGuid(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetGuid(i - PrivateVisibleFieldCount);

        TypeAffinity affinity = VerifyType(i, DbType.Guid);
        if (affinity == TypeAffinity.Blob)
        {
            byte[] buffer = new byte[16];
            _activeStatement._sql.GetBytes(_activeStatement, i, 0, buffer, 0, 16);
            return new Guid(buffer);
        }
        else
            return new Guid(_activeStatement._sql.GetText(_activeStatement, i));
    }

    /// <summary>
    /// Returns the column as a short
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>Int16</returns>
    public override Int16 GetInt16(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetInt16(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Int16);
        return Convert.ToInt16(_activeStatement._sql.GetInt32(_activeStatement, i));
    }

    /// <summary>
    /// Retrieves the column as an int
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>Int32</returns>
    public override Int32 GetInt32(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetInt32(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Int32);
        return _activeStatement._sql.GetInt32(_activeStatement, i);
    }

    /// <summary>
    /// Retrieves the column as a long
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>Int64</returns>
    public override Int64 GetInt64(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetInt64(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.Int64);
        return _activeStatement._sql.GetInt64(_activeStatement, i);
    }

    /// <summary>
    /// Retrieves the name of the column
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>string</returns>
    public override string GetName(int i)
    {
        CheckDisposed();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetName(i - PrivateVisibleFieldCount);

        return _activeStatement._sql.ColumnName(_activeStatement, i);
    }

    /// <summary>
    /// Retrieves the i of a column, given its name
    /// </summary>
    /// <param name="name">The name of the column to retrieve</param>
    /// <returns>The int i of the column</returns>
    public override int GetOrdinal(string name)
    {
      CheckDisposed();
      VerifyForGet();

      if (_throwOnDisposed) SQLiteCommand.Check(_command);

      //
      // NOTE: First, check if the column name cache has been initialized yet.
      //       If not, do it now.
      //
      if (_fieldIndexes == null)

      if (!_fieldIndexes.TryGetValue(name, out r))
      {
          r = _activeStatement._sql.ColumnIndex(_activeStatement, name);

          if (r == -1 && _keyInfo != null)
          {
              r = _keyInfo.GetOrdinal(name);
              if (r > -1) r += PrivateVisibleFieldCount;
          }

          _fieldIndexes.Add(name, r);
      }

      return r;
    }

    /// <summary>
    /// Retrieves the column as a string
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>string</returns>
    public override string GetString(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetString(i - PrivateVisibleFieldCount);

        VerifyType(i, DbType.String);
        return _activeStatement._sql.GetText(_activeStatement, i);
    }

    /// <summary>
    /// Retrieves the column as an object corresponding to the underlying datatype of the column
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>object</returns>
    public override object GetValue(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.GetValue(i - PrivateVisibleFieldCount);

        SQLiteType typ = GetSQLiteType(_flags, i);

        if (((_flags & SQLiteConnectionFlags.DetectTextAffinity) == SQLiteConnectionFlags.DetectTextAffinity) &&
            ((typ == null) || (typ.Affinity == TypeAffinity.Text)))
        {
            typ = GetSQLiteType(
                typ, _activeStatement._sql.GetText(_activeStatement, i));
        }
        else if (((_flags & SQLiteConnectionFlags.DetectStringType) == SQLiteConnectionFlags.DetectStringType) &&
            ((typ == null) || SQLiteConvert.IsStringDbType(typ.Type)))
        {
            typ = GetSQLiteType(
                typ, _activeStatement._sql.GetText(_activeStatement, i));
        }

        return _activeStatement._sql.GetValue(_activeStatement, _flags, i, typ);
    }

    /// <summary>
    /// Retreives the values of multiple columns, up to the size of the supplied array
    /// </summary>
    /// <param name="values">The array to fill with values from the columns in the current resultset</param>
    /// <returns>The number of columns retrieved</returns>

    public NameValueCollection GetValues()
    {
        CheckDisposed();

        if ((_activeStatement == null) || (_activeStatement._sql == null))
            throw new InvalidOperationException();

        int nMax = PrivateVisibleFieldCount;
        NameValueCollection result = new NameValueCollection(nMax);

        for (int n = 0; n < nMax; n++)
        {
            string name = _activeStatement._sql.ColumnName(_activeStatement, n);
            string value = _activeStatement._sql.GetText(_activeStatement, n);

    /// <summary>
    /// Returns True if the specified column is null
    /// </summary>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>True or False</returns>
    public override bool IsDBNull(int i)
    {
        CheckDisposed();
        VerifyForGet();

        if (i >= PrivateVisibleFieldCount && _keyInfo != null)
            return _keyInfo.IsDBNull(i - PrivateVisibleFieldCount);

        return _activeStatement._sql.IsNull(_activeStatement, i);
    }

    /// <summary>
    /// Moves to the next resultset in multiple row-returning SQL command.
    /// </summary>
    /// <returns>True if the command was successful and a new resultset is available, False otherwise.</returns>
    public override bool NextResult()

            _readingState = 1; // This command returned columns but no rows, so return true, but HasRows = false and Read() returns false
          }
        }

        // Ahh, we found a row-returning resultset eligible to be returned!
        _activeStatement = stmt;
        _fieldCount = fieldCount;
        _fieldIndexes = new Dictionary<string, int>(StringComparer.OrdinalIgnoreCase);
        _fieldTypeArray = new SQLiteType[PrivateVisibleFieldCount];

        if ((_commandBehavior & CommandBehavior.KeyInfo) != 0)
          LoadKeyInfo();

        return true;
      }
    }

    /// Retrieves the SQLiteType for a given column, and caches it to avoid repetetive interop calls.
    /// </summary>
    /// <param name="flags">The flags associated with the parent connection object.</param>
    /// <param name="i">The index of the column to retrieve</param>
    /// <returns>A SQLiteType structure</returns>
    private SQLiteType GetSQLiteType(SQLiteConnectionFlags flags, int i)
    {
        SQLiteType typ = _fieldTypeArray[i];


        if (typ == null)

        {
            // Initialize this column's field type instance
            typ = _fieldTypeArray[i] = new SQLiteType();
        }


        // If not initialized, then fetch the declared column datatype and attempt to convert it
        // to a known DbType.
        if (typ.Affinity == TypeAffinity.Uninitialized)
        {
            typ.Type = SQLiteConvert.TypeNameToDbType(
                GetConnection(this), _activeStatement._sql.ColumnType(
                _activeStatement, i, out typ.Affinity), flags);
        }
        else
        {
            typ.Affinity = _activeStatement._sql.ColumnAffinity(
                _activeStatement, i);
        }

        return typ;
    }

    /// <summary>
    /// Reads the next row from the resultset
    /// </summary>
    /// <returns>True if a new row was successfully loaded and is ready for processing</returns>
    public override bool Read()

  /// </summary>
  public sealed class SQLiteTransaction : DbTransaction
  {
    /// <summary>
    /// The connection to which this transaction is bound
    /// </summary>
    internal SQLiteConnection _cnn;
    internal int _version; // Matches the version of the connection
    private IsolationLevel _level;

    /// <summary>
    /// Constructs the transaction object, binding it to the supplied connection
    /// </summary>
    /// <param name="connection">The connection to open a transaction on</param>
    /// <param name="deferredLock">TRUE to defer the writelock, or FALSE to lock immediately</param>