function.db2-prepare.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Prepares an SQL statement to be executed</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.db2-pconnect.html">db2_pconnect</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.db2-primary-keys.html">db2_primary_keys</a></div> <div class="up"><a href="ref.ibm-db2.html">IBM DB2 Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.db2-prepare" class="refentry"> <div class="refnamediv"> <h1 class="refname">db2_prepare</h1> <p class="verinfo">(PECL ibm_db2:1.0-1.6.2)</p><p class="refpurpose"><span class="refname">db2_prepare</span> — <span class="dc-title"> Prepares an SQL statement to be executed </span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">resource</span> <span class="methodname"><b><b>db2_prepare</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$connection</tt></span> , <span class="methodparam"><span class="type">string</span> <tt class="parameter">$statement</tt></span> [, <span class="methodparam"><span class="type">array</span> <tt class="parameter">$options</tt></span> ] )</div> <p class="para rdfs-comment"> <b>db2_prepare()</b> creates a prepared SQL statement which can include 0 or more parameter markers (<i>?</i> characters) representing parameters for input, output, or input/output. You can pass parameters to the prepared statement using <a href="function.db2-bind-param.html" class="function">db2_bind_param()</a>, or for input values only, as an array passed to <a href="function.db2-execute.html" class="function">db2_execute()</a>. </p> <p class="para"> There are three main advantages to using prepared statements in your application: <ul class="itemizedlist"> <li class="listitem"> <p class="para"> <em class="emphasis">Performance</em>: when you prepare a statement, the database server creates an optimized access plan for retrieving data with that statement. Subsequently issuing the prepared statement with <a href="function.db2-execute.html" class="function">db2_execute()</a> enables the statements to reuse that access plan and avoids the overhead of dynamically creating a new access plan for every statement you issue. </p> </li> <li class="listitem"> <p class="para"> <em class="emphasis">Security</em>: when you prepare a statement, you can include parameter markers for input values. When you execute a prepared statement with input values for placeholders, the database server checks each input value to ensure that the type matches the column definition or parameter definition. </p> </li> <li class="listitem"> <p class="para"> <em class="emphasis">Advanced functionality</em>: Parameter markers not only enable you to pass input values to prepared SQL statements, they also enable you to retrieve OUT and INOUT parameters from stored procedures using <a href="function.db2-bind-param.html" class="function">db2_bind_param()</a>. </p> </li> </ul> </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">connection</tt></i></span> <dd> <p class="para"> A valid database connection resource variable as returned from <a href="function.db2-connect.html" class="function">db2_connect()</a> or <a href="function.db2-pconnect.html" class="function">db2_pconnect()</a>. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">statement</tt></i></span> <dd> <p class="para"> An SQL statement, optionally containing one or more parameter markers.. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">options</tt></i></span> <dd> <p class="para"> An associative array containing statement options. You can use this parameter to request a scrollable cursor on database servers that support this functionality. <dl> <dt> <br /><span class="term"><i><tt class="parameter">cursor</tt></i></span> <dd> <p class="para"> Passing the <i>DB2_FORWARD_ONLY</i> value requests a forward-only cursor for this SQL statement. This is the default type of cursor, and it is supported by all database servers. It is also much faster than a scrollable cursor. </p> <p class="para"> Passing the <i>DB2_SCROLLABLE</i> value requests a scrollable cursor for this SQL statement. This type of cursor enables you to fetch rows non-sequentially from the database server. However, it is only supported by DB2 servers, and is much slower than forward-only cursors. </p> </dd> </dt> </dl> </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns a statement resource if the SQL statement was successfully parsed and prepared by the database server. Returns <b><tt>FALSE</tt></b> if the database server returned an error. You can determine which error was returned by calling <a href="function.db2-stmt-error.html" class="function">db2_stmt_error()</a> or <a href="function.db2-stmt-errormsg.html" class="function">db2_stmt_errormsg()</a>. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 Preparing and executing an SQL statement with parameter markers</b></p> <div class="example-contents"><p> The following example prepares an INSERT statement that accepts four parameter markers, then iterates over an array of arrays containing the input values to be passed to <a href="function.db2-execute.html" class="function">db2_execute()</a>. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$animals </span><span style="color: #007700">= array(<br /> array(</span><span style="color: #0000BB">0</span><span style="color: #007700">, </span><span style="color: #DD0000">'cat'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Pook'</span><span style="color: #007700">, </span><span style="color: #0000BB">3.2</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #DD0000">'dog'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Peaches'</span><span style="color: #007700">, </span><span style="color: #0000BB">12.3</span><span style="color: #007700">),<br /> array(</span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #DD0000">'horse'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Smarty'</span><span style="color: #007700">, </span><span style="color: #0000BB">350.0</span><span style="color: #007700">),<br />);<br /><br /></span><span style="color: #0000BB">$insert </span><span style="color: #007700">= </span><span style="color: #DD0000">'INSERT INTO animals (id, breed, name, weight)<br /> VALUES (?, ?, ?, ?)'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$stmt </span><span style="color: #007700">= </span><span style="color: #0000BB">db2_prepare</span><span style="color: #007700">(</span><span style="color: #0000BB">$conn</span><span style="color: #007700">, </span><span style="color: #0000BB">$insert</span><span style="color: #007700">);<br />if (</span><span style="color: #0000BB">$stmt</span><span style="color: #007700">) {<br /> foreach (</span><span style="color: #0000BB">$animals </span><span style="color: #007700">as </span><span style="color: #0000BB">$animal</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">db2_execute</span><span style="color: #007700">(</span><span style="color: #0000BB">$stmt</span><span style="color: #007700">, </span><span style="color: #0000BB">$animal</span><span style="color: #007700">);<br /> }<br />}<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.db2-bind-param.html" class="function" rel="rdfs-seeAlso">db2_bind_param()</a></li> <li class="member"><a href="function.db2-execute.html" class="function" rel="rdfs-seeAlso">db2_execute()</a></li> <li class="member"><a href="function.db2-stmt-error.html" class="function" rel="rdfs-seeAlso">db2_stmt_error()</a></li> <li class="member"><a href="function.db2-stmt-errormsg.html" class="function" rel="rdfs-seeAlso">db2_stmt_errormsg()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.db2-pconnect.html">db2_pconnect</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.db2-primary-keys.html">db2_primary_keys</a></div> <div class="up"><a href="ref.ibm-db2.html">IBM DB2 Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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