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<div id="function.pg-prepare" class="refentry">
<div class="refnamediv">
<h1 class="refname">pg_prepare</h1>
<p class="verinfo">(PHP 5 >= 5.1.0, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">pg_prepare</span> — <span class="dc-title">
Submits a request to the server to create a prepared statement with the
given parameters, and waits for completion
</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.pg-prepare-description">
<h3 class="title">说明</h3>
<div class="methodsynopsis dc-description">
<span class="methodname"><strong>pg_prepare</strong></span>(<span class="methodparam"><span class="type"><a href="class.pgsql-connection.php" class="type PgSql\Connection">PgSql\Connection</a></span> <code class="parameter">$connection</code><span class="initializer"> = ?</span></span>, <span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$stmtname</code></span>, <span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$query</code></span>): <span class="type"><span class="type"><a href="class.pgsql-result.php" class="type PgSql\Result">PgSql\Result</a></span>|<span class="type"><a href="language.types.singleton.php" class="type false">false</a></span></span></div>
<p class="para rdfs-comment">
<span class="function"><strong>pg_prepare()</strong></span> creates a prepared statement for later execution with
<span class="function"><a href="function.pg-execute.php" class="function">pg_execute()</a></span> or <span class="function"><a href="function.pg-send-execute.php" class="function">pg_send_execute()</a></span>.
This feature allows commands that will be used repeatedly to
be parsed and planned just once, rather than each time they are executed.
<span class="function"><strong>pg_prepare()</strong></span> is supported only against PostgreSQL 7.4 or
higher connections; it will fail when using earlier versions.
</p>
<p class="para">
The function creates a prepared statement named <code class="parameter">stmtname</code> from the <code class="parameter">query</code>
string, which must contain a single SQL command. <code class="parameter">stmtname</code> may be <code class="literal">""</code> to
create an unnamed statement, in which case any pre-existing unnamed
statement is automatically replaced; otherwise it is an error if the
statement name is already defined in the current session. If any parameters
are used, they are referred to in the <code class="parameter">query</code> as <code class="literal">$1</code>,
<code class="literal">$2</code>, etc.
</p>
<p class="para">
Prepared statements for use with <span class="function"><strong>pg_prepare()</strong></span> can also be created by
executing SQL <code class="literal">PREPARE</code> statements. (But <span class="function"><strong>pg_prepare()</strong></span> is
more flexible since it does not require parameter types to be pre-specified.) Also,
although there is no PHP function for deleting a prepared statement, the
SQL <code class="literal">DEALLOCATE</code> statement can be used for that purpose.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.pg-prepare-parameters">
<h3 class="title">参数</h3>
<p class="para">
<dl>
<dt><code class="parameter">connection</code></dt>
<dd>
<p class="para">An <span class="classname"><a href="class.pgsql-connection.php" class="classname">PgSql\Connection</a></span> instance.
When <code class="parameter">connection</code> is unspecified, the default connection is used.
The default connection is the last connection made by <span class="function"><a href="function.pg-connect.php" class="function">pg_connect()</a></span>
or <span class="function"><a href="function.pg-pconnect.php" class="function">pg_pconnect()</a></span>.
<div class="warning"><strong class="warning">警告</strong><p class="simpara">As of PHP 8.1.0, using the default connection is deprecated.</p></div></p>
</dd>
<dt><code class="parameter">stmtname</code></dt>
<dd>
<p class="para">
The name to give the prepared statement. Must be unique per-connection. If
<code class="literal">""</code> is specified, then an unnamed statement is created, overwriting any
previously defined unnamed statement.
</p>
</dd>
<dt><code class="parameter">query</code></dt>
<dd>
<p class="para">
The parameterized SQL statement. Must contain only a single statement
(multiple statements separated by semi-colons are not allowed). If any parameters
are used, they are referred to as <code class="literal">$1</code>, <code class="literal">$2</code>, etc.
</p>
</dd>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.pg-prepare-returnvalues">
<h3 class="title">返回值</h3>
<p class="para">
An <span class="classname"><a href="class.pgsql-result.php" class="classname">PgSql\Result</a></span> instance on success, 或者在失败时返回 <strong><code><a href="reserved.constants.php#constant.false">false</a></code></strong>.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-function.pg-prepare-changelog">
<h3 class="title">更新日志</h3>
<table class="doctable informaltable">
<thead>
<tr>
<th>版本</th>
<th>说明</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>8.1.0</td>
<td>
现在返回 <span class="classname"><a href="class.pgsql-result.php" class="classname">PgSql\Result</a></span>
实例，之前返回 <span class="type"><a href="language.types.resource.php" class="type resource">resource</a></span>
</td>
</tr>
<tr>
<td>8.1.0</td>
<td>
现在 <code class="parameter">connection</code> 参数接受 <span class="classname"><a href="class.pgsql-connection.php" class="classname">PgSql\Connection</a></span>
实例，之前接受 <span class="type"><a href="language.types.resource.php" class="type resource">resource</a></span>。
</td>
</tr>
</tbody>
</table>
</div>
<div class="refsect1 examples" id="refsect1-function.pg-prepare-examples">
<h3 class="title">示例</h3>
<p class="para">
<div class="example" id="example-2077">
<p><strong>示例 #1 Using <span class="function"><strong>pg_prepare()</strong></span></strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">// Connect to a database named "mary"<br /></span><span style="color: #0000BB">$dbconn </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"dbname=mary"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Prepare a query for execution<br /></span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_prepare</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbconn</span><span style="color: #007700">, </span><span style="color: #DD0000">"my_query"</span><span style="color: #007700">, </span><span style="color: #DD0000">'SELECT * FROM shops WHERE name = $1'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Execute the prepared query. Note that it is not necessary to escape<br />// the string "Joe's Widgets" in any way<br /></span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_execute</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbconn</span><span style="color: #007700">, </span><span style="color: #DD0000">"my_query"</span><span style="color: #007700">, array(</span><span style="color: #DD0000">"Joe's Widgets"</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">// Execute the same prepared query, this time with a different parameter<br /></span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_execute</span><span style="color: #007700">(</span><span style="color: #0000BB">$dbconn</span><span style="color: #007700">, </span><span style="color: #DD0000">"my_query"</span><span style="color: #007700">, array(</span><span style="color: #DD0000">"Clothes Clothes Clothes"</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">?></span></span></code></div>
</div>
</div>
</p>
</div>
<div class="refsect1 seealso" id="refsect1-function.pg-prepare-seealso">
<h3 class="title">参见</h3>
<p class="para">
<ul class="simplelist">
<li><span class="function"><a href="function.pg-execute.php" class="function" rel="rdfs-seeAlso">pg_execute()</a> - Sends a request to execute a prepared statement with given parameters, and waits for the result</span></li>
<li><span class="function"><a href="function.pg-send-execute.php" class="function" rel="rdfs-seeAlso">pg_send_execute()</a> - Sends a request to execute a prepared statement with given parameters, without waiting for the result(s)</span></li>
</ul>
</p>
</div>
</div><?php manual_footer($setup); ?>