Registers a User Defined Function for use in SQL statements


(PHP 5 >= 5.1.0, PECL pdo_sqlite >= 1.0.0)

PDO::sqliteCreateFunction Registers a User Defined Function for use in SQL statements

Описание

public bool PDO::sqliteCreateFunction ( string $function_name , callable $callback [, int $num_args ] )
Внимание

Эта функция является ЭКСПЕРИМЕНТАЛЬНОЙ. Поведение этой функции, ее имя и относящаяся к ней документация могут измениться в последующих версиях PHP без уведомления. Используйте эту функцию на свой страх и риск.

This method allows you to register a PHP function with SQLite as an UDF (User Defined Function), so that it can be called from within your SQL statements.

The UDF can be used in any SQL statement that can call functions, such as SELECT and UPDATE statements and also in triggers.

Список параметров

function_name

The name of the function used in SQL statements.

callback

Callback function to handle the defined SQL function.

Замечание: Callback functions should return a type understood by SQLite (i.e. scalar type).

num_args

Hint to the SQLite parser if the callback function accepts a predetermined number of arguments.

Возвращаемые значения

Возвращает TRUE в случае успешного завершения или FALSE в случае возникновения ошибки.

Примеры

Пример #1 PDO::sqliteCreateFunction() example

<?php
function md5_and_reverse($string
{
    return 
strrev(md5($string));
}

$db = new PDO('sqlite:sqlitedb');
$db->sqliteCreateFunction('md5rev''md5_and_reverse'1);
$rows $db->query('SELECT md5rev(filename) FROM files')->fetchAll();
?>

In this example, we have a function that calculates the md5 sum of a string, and then reverses it. When the SQL statement executes, it returns the value of the filename transformed by our function. The data returned in $rows contains the processed result.

The beauty of this technique is that you do not need to process the result using a foreach loop after you have queried for the data.

Подсказка

You can use PDO::sqliteCreateFunction and PDO::sqliteCreateAggregate to override SQLite native SQL functions.

Замечание:

This method is not available with the SQLite2 driver. Use the old style sqlite API for that instead.

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