183 lines
6.9 KiB
HTML
183 lines
6.9 KiB
HTML
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<!DOCTYPE html>
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<html><head>
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<link href="../sqlite.css" rel="stylesheet">
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<title>Convenience Routines For Running Queries</title>
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<!-- path=../ -->
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</head>
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<body>
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<div class=nosearch>
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<a href="../index.html">
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<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0">
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</a>
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<div><!-- IE hack to prevent disappearing logo --></div>
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<div class="tagline desktoponly">
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Small. Fast. Reliable.<br>Choose any three.
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</div>
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<div class="menu mainmenu">
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<ul>
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<li><a href="../index.html">Home</a>
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<li class='mobileonly'><a href="javascript:void(0)" onclick='toggle_div("submenu")'>Menu</a>
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<li class='wideonly'><a href='../about.html'>About</a>
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<li class='desktoponly'><a href="../docs.html">Documentation</a>
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<li class='desktoponly'><a href="../download.html">Download</a>
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<li class='wideonly'><a href='../copyright.html'>License</a>
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<li class='desktoponly'><a href="../support.html">Support</a>
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<li class='desktoponly'><a href="../prosupport.html">Purchase</a>
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<li class='search' id='search_menubutton'>
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<a href="javascript:void(0)" onclick='toggle_search()'>Search</a>
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</ul>
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</div>
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<div class="menu submenu" id="submenu">
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<ul>
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<li><a href='../about.html'>About</a>
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<li><a href='../docs.html'>Documentation</a>
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<li><a href='../download.html'>Download</a>
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<li><a href='../support.html'>Support</a>
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<li><a href='../prosupport.html'>Purchase</a>
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</ul>
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</div>
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<div class="searchmenu" id="searchmenu">
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<form method="GET" action="../search">
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<select name="s" id="searchtype">
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<option value="d">Search Documentation</option>
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<option value="c">Search Changelog</option>
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</select>
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<input type="text" name="q" id="searchbox" value="">
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<input type="submit" value="Go">
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</form>
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</div>
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</div>
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<script>
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function toggle_div(nm) {
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var w = document.getElementById(nm);
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if( w.style.display=="block" ){
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w.style.display = "none";
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}else{
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w.style.display = "block";
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}
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}
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function toggle_search() {
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var w = document.getElementById("searchmenu");
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if( w.style.display=="block" ){
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w.style.display = "none";
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} else {
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w.style.display = "block";
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setTimeout(function(){
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document.getElementById("searchbox").focus()
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}, 30);
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}
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}
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function div_off(nm){document.getElementById(nm).style.display="none";}
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window.onbeforeunload = function(e){div_off("submenu");}
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/* Disable the Search feature if we are not operating from CGI, since */
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/* Search is accomplished using CGI and will not work without it. */
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if( !location.origin || !location.origin.match || !location.origin.match(/http/) ){
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document.getElementById("search_menubutton").style.display = "none";
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}
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/* Used by the Hide/Show button beside syntax diagrams, to toggle the */
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function hideorshow(btn,obj){
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var x = document.getElementById(obj);
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var b = document.getElementById(btn);
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if( x.style.display!='none' ){
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x.style.display = 'none';
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b.innerHTML='show';
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}else{
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x.style.display = '';
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b.innerHTML='hide';
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}
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return false;
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}
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</script>
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</div>
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<!-- keywords: sqlite3_free_table sqlite3_get_table -->
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<div class=nosearch>
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<a href="intro.html"><h2>SQLite C Interface</h2></a>
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<h2>Convenience Routines For Running Queries</h2>
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</div>
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<blockquote><pre>
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int sqlite3_get_table(
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sqlite3 *db, /* An open database */
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const char *zSql, /* SQL to be evaluated */
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char ***pazResult, /* Results of the query */
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int *pnRow, /* Number of result rows written here */
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int *pnColumn, /* Number of result columns written here */
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char **pzErrmsg /* Error msg written here */
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);
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void sqlite3_free_table(char **result);
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</pre></blockquote>
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<p>
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This is a legacy interface that is preserved for backwards compatibility.
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Use of this interface is not recommended.</p>
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<p>Definition: A <b>result table</b> is memory data structure created by the
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<a href="../c3ref/free_table.html">sqlite3_get_table()</a> interface. A result table records the
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complete query results from one or more queries.</p>
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<p>The table conceptually has a number of rows and columns. But
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these numbers are not part of the result table itself. These
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numbers are obtained separately. Let N be the number of rows
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and M be the number of columns.</p>
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<p>A result table is an array of pointers to zero-terminated UTF-8 strings.
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There are (N+1)*M elements in the array. The first M pointers point
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to zero-terminated strings that contain the names of the columns.
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The remaining entries all point to query results. NULL values result
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in NULL pointers. All other values are in their UTF-8 zero-terminated
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string representation as returned by <a href="../c3ref/column_blob.html">sqlite3_column_text()</a>.</p>
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<p>A result table might consist of one or more memory allocations.
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It is not safe to pass a result table directly to <a href="../c3ref/free.html">sqlite3_free()</a>.
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A result table should be deallocated using <a href="../c3ref/free_table.html">sqlite3_free_table()</a>.</p>
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<p>As an example of the result table format, suppose a query result
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is as follows:</p>
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<p><blockquote><pre>
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Name | Age
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-----------------------
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Alice | 43
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Bob | 28
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Cindy | 21
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</pre></blockquote></p>
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<p>There are two columns (M==2) and three rows (N==3). Thus the
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result table has 8 entries. Suppose the result table is stored
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in an array named azResult. Then azResult holds this content:</p>
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<p><blockquote><pre>
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azResult[0] = "Name";
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azResult[1] = "Age";
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azResult[2] = "Alice";
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azResult[3] = "43";
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azResult[4] = "Bob";
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azResult[5] = "28";
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azResult[6] = "Cindy";
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azResult[7] = "21";
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</pre></blockquote></p>
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<p>The sqlite3_get_table() function evaluates one or more
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semicolon-separated SQL statements in the zero-terminated UTF-8
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string of its 2nd parameter and returns a result table to the
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pointer given in its 3rd parameter.</p>
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<p>After the application has finished with the result from sqlite3_get_table(),
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it must pass the result table pointer to sqlite3_free_table() in order to
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release the memory that was malloced. Because of the way the
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<a href="../c3ref/free.html">sqlite3_malloc()</a> happens within sqlite3_get_table(), the calling
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function must not try to call <a href="../c3ref/free.html">sqlite3_free()</a> directly. Only
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<a href="../c3ref/free_table.html">sqlite3_free_table()</a> is able to release the memory properly and safely.</p>
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<p>The sqlite3_get_table() interface is implemented as a wrapper around
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<a href="../c3ref/exec.html">sqlite3_exec()</a>. The sqlite3_get_table() routine does not have access
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to any internal data structures of SQLite. It uses only the public
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interface defined here. As a consequence, errors that occur in the
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wrapper layer outside of the internal <a href="../c3ref/exec.html">sqlite3_exec()</a> call are not
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reflected in subsequent calls to <a href="../c3ref/errcode.html">sqlite3_errcode()</a> or
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<a href="../c3ref/errcode.html">sqlite3_errmsg()</a>.
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</p><p>See also lists of
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<a href="objlist.html">Objects</a>,
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<a href="constlist.html">Constants</a>, and
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<a href="funclist.html">Functions</a>.</p>
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