oci-close.xml

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<refentry xml:id="function.oci-close" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>oci_close</refname>
  <refpurpose>Closes an Oracle connection</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>bool</type><type>null</type></type><methodname>oci_close</methodname>
   <methodparam><type>resource</type><parameter>connection</parameter></methodparam>
  </methodsynopsis>
  <para>
   Unsets <parameter>connection</parameter>.  The underlying database
   connection is closed if no other resources are using it and if it
   was created with <function>oci_connect</function>
   or <function>oci_new_connect</function>.
  </para>
  <para>
   It is recommended to close connections that are no longer needed
   because this makes database resources available for other users.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>connection</parameter></term>
     <listitem>
      <para>
       An Oracle connection identifier returned by 
       <function>oci_connect</function>, <function>oci_pconnect</function>,
       or <function>oci_new_connect</function>.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns &null; when <link linkend="ini.oci8.old-oci-close-semantics">oci8.old_oci_close_semantics</link> is enabled,
   or &true; otherwise.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title>Closing a connection</title>
   <para>
    Resources associated with a connection should be closed to ensure
    the underlying database connection is properly terminated and the
    database resources are released.
   </para>
   <programlisting role="php">
<![CDATA[
<?php

$conn = oci_connect('hr', 'welcome', 'localhost/XE');
if (!$conn) {
    $e = oci_error();
    trigger_error(htmlentities($e['message'], ENT_QUOTES), E_USER_ERROR);
}

$stid = oci_parse($conn, 'SELECT * FROM departments');
$r = oci_execute($stid);
oci_fetch_all($stid, $res);
var_dump($res);

// Free the statement identifier when closing the connection
oci_free_statement($stid);
oci_close($conn);

?>
]]>
   </programlisting>
  </example>

  <example>
   <title>Database connections are not closed until all references are closed</title>
   <para>
    The internal refcount of a connection identifier must be zero
    before the underlying connection to the database is closed.
   </para>
   <programlisting role="php">
<![CDATA[
<?php

$conn = oci_connect('hr', 'welcome', 'localhost/XE');
if (!$conn) {
    $e = oci_error();
    trigger_error(htmlentities($e['message'], ENT_QUOTES), E_USER_ERROR);
}

$stid = oci_parse($conn, 'SELECT * FROM departments');  // this increases the refcount on $conn
oci_execute($stid);
oci_fetch_all($stid, $res);
var_dump($res);

oci_close($conn);

// $conn is no longer usable in the script but the underlying database
// connection is still held open until $stid is freed.
var_dump($conn);  // prints NULL  

// While PHP sleeps, querying the Oracle V$SESSION view in a
// terminal window will show that the database user is still connected.
sleep(10);

// When $stid is freed, the database connection is physically closed
oci_free_statement($stid);  

// While PHP sleeps, querying the Oracle V$SESSION view in a
// terminal window will show that the database user has disconnected.
sleep(10);

?>
]]>
   </programlisting>
  </example>

  <example>
   <title>Closing a connection opened more than once</title>
   <para>
     When database credentials are reused, both connections must be closed
     before the underlying database connection is closed.
   </para>
   <programlisting role="php">
<![CDATA[
<?php

$conn1 = oci_connect('hr', 'welcome', 'localhost/XE');

// Using the same credentials reuses the same underlying database connection
// Any uncommitted changes done on $conn1 will be visible in $conn2
$conn2 = oci_connect('hr', 'welcome', 'localhost/XE');

// While PHP sleeps, querying the Oracle V$SESSION view in a
// terminal window will show that only one database user is connected.
sleep(10);

oci_close($conn1); // doesn't close the underlying database connection
var_dump($conn1);  // prints NULL because the variable $conn1 is no longer usable
var_dump($conn2);  // displays that $conn2 is still a valid connection resource

?>
]]>
   </programlisting>
  </example>

  <example>
   <title>Connections are closed when variables go out of scope</title>
   <para>
    When all variables referencing a connection go out of scope and
    are freed by PHP, a rollback occurs (if necessary) and the
    underlying connection to the database is closed.
   </para>
   <programlisting role="php">
<![CDATA[
<?php

function myfunc() {
    $conn = oci_connect('hr', 'hrpwd', 'localhost/XE');
    if (!$conn) {
        $e = oci_error();
        trigger_error(htmlentities($e['message'], ENT_QUOTES), E_USER_ERROR);
    }

    $stid = oci_parse($conn, 'UPDATE mytab SET id = 100');
    oci_execute($stid, OCI_NO_AUTO_COMMIT);
    return "Finished";
}

$r = myfunc();
// At this point a rollback occurred and the underlying database connection was released.

print $r;  // displays the function return value "Finished"

?>
]]>
   </programlisting>
  </example>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    Variables that have a dependency on the connection identifier,
    such as statement identifiers returned
    by <function>oci_parse</function>, must also be freed before the
    underlying database connection is closed.
   </para>
  </note>
  <note>
   <para>
    The <function>oci_close</function> function does not close the
    underlying database connections created
    with <function>oci_pconnect</function>.
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>oci_connect</function></member>
    <member><function>oci_free_statement</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>
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