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<span id="runningHeaderText">CREATE INDEX</span> </td>
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<span id="nsrTitle">SQLite Language Reference Documentation</span>
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<h1 class="heading">
SQL As Understood By SQLite</h1>
<h4>
CREATE INDEX</h4>
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<i><font color="#ff3434">sql-statement</font></i> ::=</td>
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<b><font color="#2c2cf0">CREATE </font></b>[<b><font color="#2c2cf0">UNIQUE</font></b>]<b><font
color="#2c2cf0"> INDEX </font></b>[<b><font color="#2c2cf0">IF NOT EXISTS</font></b>]<b><font
color="#2c2cf0"> </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">index-name</font></i><b><font color="#2c2cf0">
<br />
ON </font></b><i><font color="#ff3434">table-name</font></i><b><font color="#2c2cf0">
<big>(</big> </font></b><i><font color="#ff3434">column-name</font></i><b><font color="#2c2cf0">
</font></b>[<b><font color="#2c2cf0"><big>,</big> </font></b><i><font color="#ff3434">
column-name</font></i><b><font color="#2c2cf0"></font></b>]<b><font color="#2c2cf0"></font></b><big>*</big><b><font
color="#2c2cf0"> <big>)</big></font></b></td>
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<i><font color="#ff3434">column-name</font></i> ::=</td>
<td>
<b><font color="#2c2cf0"></font></b><i><font color="#ff3434">name</font></i><b><font
color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0"> COLLATE </font></b><i><font
color="#ff3434">collation-name</font></i><b><font color="#2c2cf0"></font></b>]<b><font
color="#2c2cf0"> </font></b>[<b><font color="#2c2cf0"> ASC </font></b><big>|</big><b><font
color="#2c2cf0"> DESC </font></b>]<b><font color="#2c2cf0"></font></b></td>
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<p>
The CREATE INDEX command consists of the keywords "CREATE INDEX" followed by the
name of the new index, the keyword "ON", the name of a previously created table
that is to be indexed, and a parenthesized list of names of columns in the table
that are used for the index key. Each column name can be followed by one of the
"ASC" or "DESC" keywords to indicate sort order, but the sort order is ignored in
the current implementation. Sorting is always done in ascending order.</p>
<p>
The COLLATE clause following each column name defines a collating sequence used
for text entires in that column. The default collating sequence is the collating
sequence defined for that column in the CREATE TABLE statement. Or if no collating
sequence is otherwise defined, the built-in BINARY collating sequence is used.</p>
<p>
There are no arbitrary limits on the number of indices that can be attached to a
single table, nor on the number of columns in an index.</p>
<p>
If the UNIQUE keyword appears between CREATE and INDEX then duplicate index entries
are not allowed. Any attempt to insert a duplicate entry will result in an error.</p>
<p>
The exact text of each CREATE INDEX statement is stored in the <b>sqlite_master</b>
or <b>sqlite_temp_master</b> table, depending on whether the table being indexed
is temporary. Every time the database is opened, all CREATE INDEX statements are
read from the <b>sqlite_master</b> table and used to regenerate
SQLite's internal
representation of the index layout.</p>
<p>
If the optional IF NOT EXISTS clause is present and another index with the same name aleady exists, then this command becomes a no-op.</p>
<p>
Indexes are removed with the <a href="lang_dropindex.html">DROP INDEX</a> command.</p>
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