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<span id="runningHeaderText">ALTER TABLE</span> </td>
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<h1 class="heading">
SQL As Understood By SQLite</h1>
<h4>
ALTER TABLE</h4>
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<i><font color="#ff3434">sql-statement</font></i> ::=</td>
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<b><font color="#2c2cf0">ALTER TABLE </font></b>[<b><font color="#2c2cf0"></font></b><i><font
color="#ff3434">database-name</font></i><b><font color="#2c2cf0"> <big>.</big></font></b>]<b><font
color="#2c2cf0"> </font></b><i><font color="#ff3434">table-name</font></i><b><font
color="#2c2cf0"> </font></b><i><font color="#ff3434">alteration</font></i><b><font
color="#2c2cf0"></font></b></td>
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<i><font color="#ff3434">alteration</font></i> ::=</td>
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<b><font color="#2c2cf0">RENAME TO </font></b><i><font color="#ff3434">new-table-name</font></i><b><font
color="#2c2cf0"></font></b></td>
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<i><font color="#ff3434">alteration</font></i> ::=</td>
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<b><font color="#2c2cf0">ADD </font></b>[<b><font color="#2c2cf0">COLUMN</font></b>]<b><font
color="#2c2cf0"> </font></b><i><font color="#ff3434">column-def</font></i><b><font
color="#2c2cf0"></font></b></td>
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</p>
<p>
SQLite's version of the ALTER TABLE command allows the user to rename or add a new
column to an existing table. It is not possible to remove a column from a table.
</p>
<p>
The RENAME TO syntax is used to rename the table identified by <i>[database-name.]table-name</i>
to <i>new-table-name</i>. This command cannot be used to move a table between attached
databases, only to rename a table within the same database.</p>
<p>
If the table being renamed has triggers or indices, then these remain attached to
the table after it has been renamed. However, if there are any view definitions,
or statements executed by triggers that refer to the table being renamed, these
are not automatically modified to use the new table name. If this is required, the
triggers or view definitions must be dropped and recreated to use the new table
name by hand.
</p>
<p>
The ADD [COLUMN] syntax is used to add a new column to an existing table. The new
column is always appended to the end of the list of existing columns. <i>Column-def</i>
may take any of the forms permissable in a CREATE TABLE statement, with the following
restrictions:
</p>
<ul>
<li>The column may not have a PRIMARY KEY or UNIQUE constraint. </li>
<li>The column may not have a default value of CURRENT_TIME, CURRENT_DATE or CURRENT_TIMESTAMP.
</li>
<li>If a NOT NULL constraint is specified, then the column must have a default value
other than NULL. </li>
</ul>
<p>
The execution time of the ALTER TABLE command is independent of the amount of data
in the table. The ALTER TABLE command runs as quickly on a table with 10 million
rows as it does on a table with 1 row.
</p>
<p>
After ADD COLUMN has been run on a database, that database will not be readable
by SQLite version 3.1.3 and earlier until the database is <a href="lang_vacuum.html">
VACUUM</a>ed.</p>
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