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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"><html><head><title>Count The Number Of Rows Modified</title><style type="text/css">body { margin: auto; font-family: "Verdana" "sans-serif"; padding: 8px 1%;}a { color: #45735f }a:visited { color: #734559 }.logo { position:absolute; margin:3px; }.tagline { float:right; text-align:right; font-style:italic; width:240px; margin:12px; margin-top:58px;}.toolbar { font-variant: small-caps; text-align: center; line-height: 1.6em; margin: 0; padding:1px 8px;}.toolbar a { color: white; text-decoration: none; padding: 6px 12px; }.toolbar a:visited { color: white; }.toolbar a:hover { color: #80a796; background: white; }.content { margin: 5%; }.content dt { font-weight:bold; }.content dd { margin-bottom: 25px; margin-left:20%; }.content ul { padding:0px; padding-left: 15px; margin:0px; }/* rounded corners */.se { background: url(../images/se.png) 100% 100% no-repeat #80a796}.sw { background: url(../images/sw.png) 0% 100% no-repeat }.ne { background: url(../images/ne.png) 100% 0% no-repeat }.nw { background: url(../images/nw.png) 0% 0% no-repeat }</style><meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head><body><div><!-- container div to satisfy validator --><a href="../index.html"><img class="logo" src="../images/SQLite.gif" alt="SQLite Logo" border="0"></a><div><!-- IE hack to prevent disappearing logo--></div><div class="tagline">Small. Fast. Reliable.<br>Choose any three.</div><table width=100% style="clear:both"><tr><td> <div class="se"><div class="sw"><div class="ne"><div class="nw"> <div class="toolbar"> <a href="../about.html">About</a> <a href="../sitemap.html">Sitemap</a> <a href="../docs.html">Documentation</a> <a href="../download.html">Download</a> <a href="../copyright.html">License</a> <a href="../news.html">News</a> <a href="http://www.sqlite.org/cvstrac/index">Developers</a> <a href="../support.html">Support</a> </div></div></div></div></div></td></tr></table> <a href="intro.html"><h2>SQLite C Interface</h2></a><h2>Count The Number Of Rows Modified</h2><blockquote><pre>int sqlite3_changes(sqlite3*);</pre></blockquote><p>This function returns the number of database rows that were changedor inserted or deleted by the most recently completed SQL statementon the connection specified by the first parameter. Onlychanges that are directly specified by the INSERT, UPDATE, orDELETE statement are counted. Auxiliary changes caused bytriggers are not counted. Use the <a href="../c3ref/total_changes.html">sqlite3_total_changes()</a> functionto find the total number of changes including changes caused by triggers.</p><p>A "row change" is a change to a single row of a single tablecaused by an INSERT, DELETE, or UPDATE statement. Rows thatare changed as side effects of REPLACE constraint resolution,rollback, ABORT processing, DROP TABLE, or by any othermechanisms do not count as direct row changes.</p><p>A "trigger context" is a scope of execution that begins andends with the script of a trigger. Most SQL statements areevaluated outside of any trigger. This is the "top level"trigger context. If a trigger fires from the top level, anew trigger context is entered for the duration of that onetrigger. Subtriggers create subcontexts for their duration.</p><p>Calling <a href="../c3ref/exec.html">sqlite3_exec()</a> or <a href="../c3ref/step.html">sqlite3_step()</a> recursively doesnot create a new trigger context.</p><p>This function returns the number of direct row changes in themost recent INSERT, UPDATE, or DELETE statement within the sametrigger context.</p><p>So when called from the top level, this function returns thenumber of changes in the most recent INSERT, UPDATE, or DELETEthat also occurred at the top level.Within the body of a trigger, the sqlite3_changes() interfacecan be called to find the number ofchanges in the most recently completed INSERT, UPDATE, or DELETEstatement within the body of the same trigger.However, the number returned does not include in changescaused by subtriggers since they have their own context.</p><p>SQLite implements the command "DELETE FROM table" withouta WHERE clause by dropping and recreating the table. (This is muchfaster than going through and deleting individual elements from thetable.) Because of this optimization, the deletions in"DELETE FROM table" are not row changes and will not be countedby the sqlite3_changes() or <a href="../c3ref/total_changes.html">sqlite3_total_changes()</a> functions.To get an accurate count of the number of rows deleted, use"DELETE FROM table WHERE 1" instead.</p><p><h3>Invariants:</h3><table border="0" cellpadding="5" cellspacing="0"><tr><td valign="top">F12241</td> <td valign="top">The <a href="../c3ref/changes.html">sqlite3_changes()</a> function returns the number ofrow changes caused by the most recent INSERT, UPDATE,or DELETE statement on the same database connection andwithin the same trigger context, or zero if there havenot been any qualifying row changes.</td></tr></table></p><p><h3>Limitations:</h3><table border="0" cellpadding="5" cellspacing="0"><tr><td valign="top">U12252</td> <td valign="top">If a separate thread makes changes on the same database connectionwhile <a href="../c3ref/changes.html">sqlite3_changes()</a> is running then the value returnedis unpredictable and unmeaningful.</td></tr></table></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><hr><small><i>This page last modified 2008/05/12 13:08:44 UTC</i></small></div></body></html>⌨️ 快捷键说明
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