152 lines
5.6 KiB
HTML
152 lines
5.6 KiB
HTML
<!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>SQL Keyword Checking</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='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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function toggle_search() {
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var w = document.getElementById("searchmenu");
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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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var x = document.getElementById(obj);
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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_keyword_check sqlite3_keyword_count sqlite3_keyword_name -->
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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>SQL Keyword Checking</h2>
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</div>
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<blockquote><pre>
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int sqlite3_keyword_count(void);
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int sqlite3_keyword_name(int,const char**,int*);
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int sqlite3_keyword_check(const char*,int);
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</pre></blockquote>
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<p>
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These routines provide access to the set of SQL language keywords
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recognized by SQLite. Applications can uses these routines to determine
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whether or not a specific identifier needs to be escaped (for example,
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by enclosing in double-quotes) so as not to confuse the parser.</p>
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<p>The sqlite3_keyword_count() interface returns the number of distinct
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keywords understood by SQLite.</p>
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<p>The sqlite3_keyword_name(N,Z,L) interface finds the N-th keyword and
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makes *Z point to that keyword expressed as UTF8 and writes the number
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of bytes in the keyword into *L. The string that *Z points to is not
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zero-terminated. The sqlite3_keyword_name(N,Z,L) routine returns
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SQLITE_OK if N is within bounds and SQLITE_ERROR if not. If either Z
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or L are NULL or invalid pointers then calls to
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sqlite3_keyword_name(N,Z,L) result in undefined behavior.</p>
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<p>The sqlite3_keyword_check(Z,L) interface checks to see whether or not
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the L-byte UTF8 identifier that Z points to is a keyword, returning non-zero
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if it is and zero if not.</p>
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<p>The parser used by SQLite is forgiving. It is often possible to use
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a keyword as an identifier as long as such use does not result in a
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parsing ambiguity. For example, the statement
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"CREATE TABLE BEGIN(REPLACE,PRAGMA,END);" is accepted by SQLite, and
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creates a new table named "BEGIN" with three columns named
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"REPLACE", "PRAGMA", and "END". Nevertheless, best practice is to avoid
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using keywords as identifiers. Common techniques used to avoid keyword
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name collisions include:
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<ul>
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<li> Put all identifier names inside double-quotes. This is the official
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SQL way to escape identifier names.
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<li> Put identifier names inside [...]. This is not standard SQL,
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but it is what SQL Server does and so lots of programmers use this
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technique.
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<li> Begin every identifier with the letter "Z" as no SQL keywords start
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with "Z".
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<li> Include a digit somewhere in every identifier name.
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</ul></p>
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<p>Note that the number of keywords understood by SQLite can depend on
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compile-time options. For example, "VACUUM" is not a keyword if
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SQLite is compiled with the <a href="../compile.html#omit_vacuum">-DSQLITE_OMIT_VACUUM</a> option. Also,
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new keywords may be added to future releases of SQLite.
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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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