doc-en/reference/pgsql/functions/pg-prepare.xml

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<refentry xml:id="function.pg-prepare" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>pg_prepare</refname>
  <refpurpose>
   Submits a request to the server to create a prepared statement with the
   given parameters, and waits for completion
  </refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>PgSql\Result</type><type>false</type></type><methodname>pg_prepare</methodname>
   <methodparam choice="opt"><type>PgSql\Connection</type><parameter>connection</parameter></methodparam>
   <methodparam><type>string</type><parameter>stmtname</parameter></methodparam>
   <methodparam><type>string</type><parameter>query</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>pg_prepare</function> creates a prepared statement for later execution with
   <function>pg_execute</function> or <function>pg_send_execute</function>.
   This feature allows commands that will be used repeatedly to
   be parsed and planned just once, rather than each time they are executed.
   <function>pg_prepare</function> is supported only against PostgreSQL 7.4 or
   higher connections; it will fail when using earlier versions.
  </para>
  <para>
   The function creates a prepared statement named <parameter>stmtname</parameter> from the <parameter>query</parameter>
   string, which must contain a single SQL command. <parameter>stmtname</parameter> may be <literal>""</literal> 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 <parameter>query</parameter> as <literal>$1</literal>,
   <literal>$2</literal>, etc.
  </para>
  <para>
   Prepared statements for use with <function>pg_prepare</function> can also be created by
   executing SQL <literal>PREPARE</literal> statements. (But <function>pg_prepare</function> 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 <literal>DEALLOCATE</literal> statement can be used for that purpose.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>connection</parameter></term>
     <listitem>
      &pgsql.parameter.connection-with-unspecified-default;
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>stmtname</parameter></term>
     <listitem>
      <para>
       The name to give the prepared statement.  Must be unique per-connection.  If
       <literal>""</literal> is specified, then an unnamed statement is created, overwriting any
       previously defined unnamed statement.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>query</parameter></term>
     <listitem>
      <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 <literal>$1</literal>, <literal>$2</literal>, etc.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   An <classname>PgSql\Result</classname> instance on success, &return.falseforfailure;.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     &pgsql.changelog.return-result-object;
     &pgsql.changelog.connection-object;
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>
 
 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>Using <function>pg_prepare</function></title>
    <programlisting role="php">
<![CDATA[
<?php

// Connect to a database named "mary"
$dbconn = pg_connect("dbname=mary");

// Prepare a query for execution
$result = pg_prepare($dbconn, "my_query", 'SELECT * FROM shops WHERE name = $1');

// Execute the prepared query.  Note that it is not necessary to escape
// the string "Joe's Widgets" in any way
$result = pg_execute($dbconn, "my_query", array("Joe's Widgets"));

// Execute the same prepared query, this time with a different parameter
$result = pg_execute($dbconn, "my_query", array("Clothes Clothes Clothes"));

?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>
 
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>pg_execute</function></member>
    <member><function>pg_send_execute</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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