PHP kézikönyv
Előző |  | Következő

# PDO::sqliteCreateFunction

(no version information, might be only in CVS)

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

## Leírás

bool PDO::sqliteCreateFunction ( string function_name, callback callback [, int num_args] )

Figyelem
Ez a függvény KÍSÉRLETI JELLEGGEL MŰKÖDIK. A függvény működése, neve, bármi amit a függévénnyel kapcsolatban dokumentáltunk megváltozhat egy későbbi PHP kiadásban minden figyelmeztetés nélkül. Ezt a függvényt csak a saját felelősségedre használd!

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.

## Paraméterek

function_name

  The name of the function used in SQL statements.

callback

  Callback function to handle the defined SQL function.

  > Megjegyzés: 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.

> Megjegyzés: Two alternative syntaxes are supported for compatibility with other database extensions (such as MySQL). The preferred form is the first, where the dbhandle parameter is the first parameter to the function.

## Példák

Példa 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.

> Tipp: You can use PDO::sqliteCreateFunction() and PDO::sqliteCreateAggregate() to override SQLite native SQL functions.

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

## Lásd még

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

Előző | Tartalom | Következő
PDO::sqliteCreateAggregate | Fel | Secure Shell2 Functions