# sqlite_udf_decode_binary

(PHP 5 < 5.4.0, PECL sqlite >= 1.0.0)

sqlite_udf_decode_binary — Decode binary data passed as parameters to an UDF

### 说明

sqlite_udf_decode_binary ( string `$data` ) : string

Decodes binary data passed as parameters to a UDF.

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.

PHP does not perform this encode/decode operation automatically as it would severely impact performance if it did.

### 参数

`data`

  The encoded data that will be decoded, data that was applied by either sqlite_udf_encode_binary() or sqlite_escape_string().

### 返回值

The decoded string.

### 范例

Example #1 binary-safe max_length aggregation function example

    <?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'));

    ?>

### 参见

- sqlite_udf_encode_binary() - Encode binary data before returning it from an UDF
- sqlite_create_function() - Registers a "regular" User Defined Function for use in SQL statements
- sqlite_create_aggregate() - Register an aggregating UDF for use in SQL statements