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<!-- keywords: SQLITE_LOCK_EXCLUSIVE SQLITE_LOCK_NONE SQLITE_LOCK_PENDING SQLITE_LOCK_RESERVED SQLITE_LOCK_SHARED -->
<div class=nosearch>
<a href="intro.html"><h2>SQLite C Interface</h2></a>
<h2>File Locking Levels</h2>
</div>
<blockquote><pre>
#define SQLITE_LOCK_NONE 0 /* xUnlock() only */
#define SQLITE_LOCK_SHARED 1 /* xLock() or xUnlock() */
#define SQLITE_LOCK_RESERVED 2 /* xLock() only */
#define SQLITE_LOCK_PENDING 3 /* xLock() only */
#define SQLITE_LOCK_EXCLUSIVE 4 /* xLock() only */
</pre></blockquote>
<p>
SQLite uses one of these integer values as the second
argument to calls it makes to the xLock() and xUnlock() methods
of an <a href="../c3ref/io_methods.html">sqlite3_io_methods</a> object. These values are ordered from
lest restrictive to most restrictive.</p>
<p>The argument to xLock() is always SHARED or higher. The argument to
xUnlock is either SHARED or NONE.
</p><p>See also lists of
<a href="objlist.html">Objects</a>,
<a href="constlist.html">Constants</a>, and
<a href="funclist.html">Functions</a>.</p>
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