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<?xml version='1.0' encoding='iso-8859-1'?>
<!-- $Revision: 1.11 $ -->
<!-- Generated by xml_proto.php v2.1. Found in /scripts directory of phpdoc. -->
<refentry id="function.PDO-prepare">
<refnamediv>
<refname>PDO::prepare</refname>
<refpurpose>
Prepares a statement for execution and returns a statement object
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>PDOStatement</type><methodname>PDO::prepare</methodname>
<methodparam><type>string</type><parameter>statement</parameter></methodparam>
<methodparam choice="opt"><type>array</type><parameter>driver_options</parameter></methodparam>
</methodsynopsis>
<para>
Prepares an SQL statement to be executed by the
<function>PDOStatement::execute</function> method. The SQL statement can
contain zero or more named (:name) or question mark (?) parameter markers
for which real values will be substituted when the statement is executed.
You cannot use both named and question mark parameter markers within the same
SQL statement; pick one or the other parameter style.
</para>
<para>
You must include a unique parameter marker for each value you wish to pass
in to the statement when you call <function>PDOStatement::execute</function>.
You cannot use a named parameter marker of the same name twice in a prepared
statement. You cannot bind multiple values to a single named parameter in,
for example, the IN() clause of an SQL statement.
</para>
<para>
Calling <function>PDO::prepare</function> and
<function>PDOStatement::execute</function> for statements that will be
issued multiple times with different parameter values optimizes the
performance of your application by allowing the driver to negotiate
client and/or server side caching of the query plan and meta information,
and helps to prevent SQL injection attacks by eliminating the need to
manually quote the parameters.
</para>
<para>
PDO will emulate prepared statements/bound parameters for drivers that do
not natively support them, and can also rewrite named or question mark
style parameter markers to something more appropriate, if the driver
supports one style but not the other.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>statement</parameter></term>
<listitem>
<para>
This must be a valid SQL statement for the target database server.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>driver_options</parameter></term>
<listitem>
<para>
This array holds one or more key=>value pairs to set
attribute values for the PDOStatement object that this method
returns. You would most commonly use this to set the
<literal>PDO::ATTR_CURSOR</literal> value to
<literal>PDO::CURSOR_SCROLL</literal> to request a scrollable cursor.
Some drivers have driver specific options that may be set at
prepare-time.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
If the database server successfully prepares the statement,
<function>PDO::prepare</function> returns a PDOStatement object.
If the database server cannot successfully prepare the statement,
<function>PDO::prepare</function> returns &false;.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example><title>Prepare an SQL statement with named parameters</title>
<programlisting role='php'>
<![CDATA[
<?php
/* Execute a prepared statement by passing an array of values */
$sql = 'SELECT name, colour, calories
FROM fruit
WHERE calories < :calories AND colour = :colour';
$sth = $dbh->prepare($sql, array(PDO::ATTR_CURSOR, PDO::CURSOR_FWDONLY));
$sth->execute(array(':calories' => 150, ':colour' => 'red'));
$red = $sth->fetchAll();
$sth->execute(array(':calories' => 175, ':colour' => 'yellow'));
$yellow = $sth->fetchAll();
?>
]]>
</programlisting>
</example>
<example>
<title>Prepare an SQL statement with question mark parameters</title>
<programlisting role='php'>
<![CDATA[
<?php
/* Execute a prepared statement by passing an array of values */
$sth = $dbh->prepare('SELECT name, colour, calories
FROM fruit
WHERE calories < ? AND colour = ?');
$sth->execute(array(150, 'red'));
$red = $sth->fetchAll();
$sth->execute(array(175, 'yellow'));
$yellow = $sth->fetchAll();
?>
]]>
</programlisting>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>PDO::exec</function></member>
<member><function>PDO::query</function></member>
<member><function>PDOStatement::execute</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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