php-doc-en/reference/pdo/functions/PDO-prepare.xml

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  <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>
     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=&gt;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.
    </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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