PHP: PDO::sqliteCreateFunction - Manual

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ssh2 PDO::sqliteCreateAggregate

Last updated: Sat, 27 Jan 2007

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# PDO::sqliteCreateFunction

(no version information, might be only in CVS)

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

## Описание

bool PDO::sqliteCreateFunction ( string function_name, callback 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.

PDO::sqliteCreateFunction() 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.

> Замечание: Поддерживаются два альтернативных синтаксиса для совместимости с другими расширениями баз данных (например MySQL). Предпочитаемая форма - первая, в которой параметр `dbhandle` является первым параметром функции.

## 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.

## Смотрите также

PDO::sqliteCreateAggregate()
sqlite_create_function()
sqlite_create_aggregate()

add a note User Contributed Notes
PDO::sqliteCreateFunction
mtknight at dark-phantasy dot com
22-Jan-2006 02:13
`This may be obvious to others, but I was stuck thinking this method wasn't yet implemented in release versions of PHP because I was trying to call this method statically from withing a class that extends PDO.
Since the method is only created once the SQLite driver is loaded in a given PDO instance, the only error feedback I was getting stated that sqliteCreateFunction did not exist, when in fact it did (after a fashion).`
add a note
ssh2 PDO::sqliteCreateAggregate

Last updated: Sat, 27 Jan 2007
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