php-doc-en/reference/sqlite/functions/sqlite-udf-decode-binary.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.6 $ -->
<refentry id="function.sqlite-udf-decode-binary">
 <refnamediv>
  <refname>sqlite_udf_decode_binary</refname>
  <refpurpose>Decode binary data passed as parameters to an UDF</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>sqlite_udf_decode_binary</methodname>
   <methodparam><type>string</type><parameter>data</parameter></methodparam>
  </methodsynopsis>
  <para>
   <function>sqlite_udf_decode_binary</function> decodes the binary encoding
   that was applied to the parameter by either
   <function>sqlite_udf_encode_binary</function> or
   <function>sqlite_escape_string</function>.
  </para>
  <para>
   You must call this function on parameters passed to your UDF if you need
   them to handle binary data, as the binary encoding employed by PHP will
   obscure the content and of the parameter in its natural, non-coded form.
  </para>
  <para>
   PHP does not perform this encode/decode operation automatically as it would
   severely impact performance if it did.
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>binary-safe max_length aggregation function example</title>
    <programlisting role="php">
<![CDATA[
<?php
$data = array(
   'one',
   'two',
   'three',
   'four',
   'five',
   'six',
   'seven',
   'eight',
   'nine',
   'ten',
   );
$db = sqlite_open(':memory:');
sqlite_query($db, "CREATE TABLE strings(a)");
foreach ($data as $str) {
    $str = sqlite_escape_string($str);
    sqlite_query($db, "INSERT INTO strings VALUES ('$str')");
}

function max_len_step(&$context, $string) 
{
    $string = sqlite_udf_decode_binary($string);
    if (strlen($string) > $context) {
        $context = strlen($string);
    }
}

function max_len_finalize(&$context) 
{
    return $context;
}

sqlite_create_aggregate($db, 'max_len', 'max_len_step', 'max_len_finalize');

var_dump(sqlite_array_query($db, 'SELECT max_len(a) from strings'));

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

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>sqlite_udf_encode_binary</function></member>
    <member><function>sqlite_create_function</function></member>
    <member><function>sqlite_create_aggregate</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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