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diff --git a/www/c3ref/prepare.html b/www/c3ref/prepare.html new file mode 100644 index 0000000..2909fe3 --- /dev/null +++ b/www/c3ref/prepare.html @@ -0,0 +1,267 @@ +<!DOCTYPE html> +<html><head> +<meta name="viewport" content="width=device-width, initial-scale=1.0"> +<meta http-equiv="content-type" content="text/html; charset=UTF-8"> +<link href="../sqlite.css" rel="stylesheet"> +<title>Compiling An SQL Statement</title> +<!-- path=../ --> +</head> +<body> +<div class=nosearch> +<a href="../index.html"> +<img class="logo" src="../images/sqlite370_banner.gif" alt="SQLite" border="0"> +</a> +<div><!-- IE hack to prevent disappearing logo --></div> +<div class="tagline desktoponly"> +Small. Fast. 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+b.innerHTML='show'; +}else{ +x.style.display = ''; +b.innerHTML='hide'; +} +return false; +} +var antiRobot = 0; +function antiRobotGo(){ +if( antiRobot!=3 ) return; +antiRobot = 7; +var j = document.getElementById("mtimelink"); +if(j && j.hasAttribute("data-href")) j.href=j.getAttribute("data-href"); +} +function antiRobotDefense(){ +document.body.onmousedown=function(){ +antiRobot |= 2; +antiRobotGo(); +document.body.onmousedown=null; +} +document.body.onmousemove=function(){ +antiRobot |= 2; +antiRobotGo(); +document.body.onmousemove=null; +} +setTimeout(function(){ +antiRobot |= 1; +antiRobotGo(); +}, 100) +antiRobotGo(); +} +antiRobotDefense(); +</script> +<!-- keywords: {SQL statement compiler} sqlite3_prepare sqlite3_prepare16 sqlite3_prepare16_v2 sqlite3_prepare16_v3 sqlite3_prepare_v2 sqlite3_prepare_v3 --> +<div class=nosearch> +<a href="../c3ref/intro.html"><h2>SQLite C Interface</h2></a> +<h2>Compiling An SQL Statement</h2> +</div> +<blockquote><pre> +int sqlite3_prepare( + sqlite3 *db, /* Database handle */ + const char *zSql, /* SQL statement, UTF-8 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const char **pzTail /* OUT: Pointer to unused portion of zSql */ +); +int sqlite3_prepare_v2( + sqlite3 *db, /* Database handle */ + const char *zSql, /* SQL statement, UTF-8 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const char **pzTail /* OUT: Pointer to unused portion of zSql */ +); +int sqlite3_prepare_v3( + sqlite3 *db, /* Database handle */ + const char *zSql, /* SQL statement, UTF-8 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const char **pzTail /* OUT: Pointer to unused portion of zSql */ +); +int sqlite3_prepare16( + sqlite3 *db, /* Database handle */ + const void *zSql, /* SQL statement, UTF-16 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const void **pzTail /* OUT: Pointer to unused portion of zSql */ +); +int sqlite3_prepare16_v2( + sqlite3 *db, /* Database handle */ + const void *zSql, /* SQL statement, UTF-16 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const void **pzTail /* OUT: Pointer to unused portion of zSql */ +); +int sqlite3_prepare16_v3( + sqlite3 *db, /* Database handle */ + const void *zSql, /* SQL statement, UTF-16 encoded */ + int nByte, /* Maximum length of zSql in bytes. */ + unsigned int prepFlags, /* Zero or more SQLITE_PREPARE_ flags */ + sqlite3_stmt **ppStmt, /* OUT: Statement handle */ + const void **pzTail /* OUT: Pointer to unused portion of zSql */ +); +</pre></blockquote> +<p> +To execute an SQL statement, it must first be compiled into a byte-code +program using one of these routines. Or, in other words, these routines +are constructors for the <a href="../c3ref/stmt.html">prepared statement</a> object.</p> + +<p>The preferred routine to use is <a href="../c3ref/prepare.html">sqlite3_prepare_v2()</a>. The +<a href="../c3ref/prepare.html">sqlite3_prepare()</a> interface is legacy and should be avoided. +<a href="../c3ref/prepare.html">sqlite3_prepare_v3()</a> has an extra "prepFlags" option that is used +for special purposes.</p> + +<p>The use of the UTF-8 interfaces is preferred, as SQLite currently +does all parsing using UTF-8. The UTF-16 interfaces are provided +as a convenience. The UTF-16 interfaces work by converting the +input text into UTF-8, then invoking the corresponding UTF-8 interface.</p> + +<p>The first argument, "db", is a <a href="../c3ref/sqlite3.html">database connection</a> obtained from a +prior successful call to <a href="../c3ref/open.html">sqlite3_open()</a>, <a href="../c3ref/open.html">sqlite3_open_v2()</a> or +<a href="../c3ref/open.html">sqlite3_open16()</a>. The database connection must not have been closed.</p> + +<p>The second argument, "zSql", is the statement to be compiled, encoded +as either UTF-8 or UTF-16. The sqlite3_prepare(), sqlite3_prepare_v2(), +and sqlite3_prepare_v3() +interfaces use UTF-8, and sqlite3_prepare16(), sqlite3_prepare16_v2(), +and sqlite3_prepare16_v3() use UTF-16.</p> + +<p>If the nByte argument is negative, then zSql is read up to the +first zero terminator. If nByte is positive, then it is the +number of bytes read from zSql. If nByte is zero, then no prepared +statement is generated. +If the caller knows that the supplied string is nul-terminated, then +there is a small performance advantage to passing an nByte parameter that +is the number of bytes in the input string <i>including</i> +the nul-terminator.</p> + +<p>If pzTail is not NULL then *pzTail is made to point to the first byte +past the end of the first SQL statement in zSql. These routines only +compile the first statement in zSql, so *pzTail is left pointing to +what remains uncompiled.</p> + +<p>*ppStmt is left pointing to a compiled <a href="../c3ref/stmt.html">prepared statement</a> that can be +executed using <a href="../c3ref/step.html">sqlite3_step()</a>. If there is an error, *ppStmt is set +to NULL. If the input text contains no SQL (if the input is an empty +string or a comment) then *ppStmt is set to NULL. +The calling procedure is responsible for deleting the compiled +SQL statement using <a href="../c3ref/finalize.html">sqlite3_finalize()</a> after it has finished with it. +ppStmt may not be NULL.</p> + +<p>On success, the sqlite3_prepare() family of routines return <a href="../rescode.html#ok">SQLITE_OK</a>; +otherwise an <a href="../rescode.html">error code</a> is returned.</p> + +<p>The sqlite3_prepare_v2(), sqlite3_prepare_v3(), sqlite3_prepare16_v2(), +and sqlite3_prepare16_v3() interfaces are recommended for all new programs. +The older interfaces (sqlite3_prepare() and sqlite3_prepare16()) +are retained for backwards compatibility, but their use is discouraged. +In the "vX" interfaces, the prepared statement +that is returned (the <a href="../c3ref/stmt.html">sqlite3_stmt</a> object) contains a copy of the +original SQL text. This causes the <a href="../c3ref/step.html">sqlite3_step()</a> interface to +behave differently in three ways:</p> + +<p><ol> +<li> +If the database schema changes, instead of returning <a href="../rescode.html#schema">SQLITE_SCHEMA</a> as it +always used to do, <a href="../c3ref/step.html">sqlite3_step()</a> will automatically recompile the SQL +statement and try to run it again. As many as <a href="../compile.html#max_schema_retry">SQLITE_MAX_SCHEMA_RETRY</a> +retries will occur before sqlite3_step() gives up and returns an error. +</li></p> + +<p><li> +When an error occurs, <a href="../c3ref/step.html">sqlite3_step()</a> will return one of the detailed +<a href="../rescode.html">error codes</a> or <a href="../rescode.html#extrc">extended error codes</a>. The legacy behavior was that +<a href="../c3ref/step.html">sqlite3_step()</a> would only return a generic <a href="../rescode.html#error">SQLITE_ERROR</a> result code +and the application would have to make a second call to <a href="../c3ref/reset.html">sqlite3_reset()</a> +in order to find the underlying cause of the problem. With the "v2" prepare +interfaces, the underlying reason for the error is returned immediately. +</li></p> + +<p><li> +If the specific value bound to a <a href="../lang_expr.html#varparam">host parameter</a> in the +WHERE clause might influence the choice of query plan for a statement, +then the statement will be automatically recompiled, as if there had been +a schema change, on the first <a href="../c3ref/step.html">sqlite3_step()</a> call following any change +to the <a href="../c3ref/bind_blob.html">bindings</a> of that <a href="../lang_expr.html#varparam">parameter</a>. +The specific value of a WHERE-clause <a href="../lang_expr.html#varparam">parameter</a> might influence the +choice of query plan if the parameter is the left-hand side of a <a href="../lang_expr.html#like">LIKE</a> +or <a href="../lang_expr.html#glob">GLOB</a> operator or if the parameter is compared to an indexed column +and the <a href="../compile.html#enable_stat4">SQLITE_ENABLE_STAT4</a> compile-time option is enabled. +</li> +</ol></p> + +<p><p>sqlite3_prepare_v3() differs from sqlite3_prepare_v2() only in having +the extra prepFlags parameter, which is a bit array consisting of zero or +more of the <a href="../c3ref/c_prepare_normalize.html#sqlitepreparepersistent">SQLITE_PREPARE_*</a> flags. The +sqlite3_prepare_v2() interface works exactly the same as +sqlite3_prepare_v3() with a zero prepFlags parameter. +</p><p>See also lists of + <a href="../c3ref/objlist.html">Objects</a>, + <a href="../c3ref/constlist.html">Constants</a>, and + <a href="../c3ref/funclist.html">Functions</a>.</p> + |