PDO::sqliteCreateFunction

(PHP 5 >= 5.1.0, PHP 7, PHP 8, PECL pdo_sqlite >= 1.0.0)

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

Descrizione

public PDO::sqliteCreateFunction(
    string $function_name,
    callable $callback,
    int $num_args = -1,
    int $flags = 0
): bool
Avviso

Questa funzione è SPERIMENTALE. Ovvero, il comportamento di questa funzione, il nome di questa funzione, in definitiva tutto ciò che è documentato qui può cambiare nei futuri rilasci del PHP senza preavviso. Siete avvisati, l'uso di questa funzione è a vostro rischio.

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.

Elenco dei parametri

function_name

The name of the function used in SQL statements.

callback

Callback function to handle the defined SQL function.

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

This function need to be defined as:

callback(mixed $value, mixed ...$values): mixed
value

The first argument passed to the SQL function.

values

Further arguments passed to the SQL function.

num_args

The number of arguments that the SQL function takes. If this parameter is -1, then the SQL function may take any number of arguments.

flags

A bitwise conjunction of flags. Currently, only PDO::SQLITE_DETERMINISTIC is supported, which specifies that the function always returns the same result given the same inputs within a single SQL statement.

Valori restituiti

Restituisce true in caso di successo, false in caso di fallimento.

Log delle modifiche

Versione Descrizione
7.1.4 The flags parameter has been added.

Esempi

Example #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.

Suggerimento

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

Vedere anche:

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User Contributed Notes 1 note

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-2
RoboTamer
10 years ago
groups looks like this '1,2,3,999'

<?php
/**
* int strpos ( string $haystack , mixed $needle [, int $offset = 0 ] )
*/
$dbUser = new PDO('sqlite:'.ROOT.'/var/db/users.db3');
$dbUser->sqliteCreateFunction('strpos', 'strpos', 2);
$sql = 'SELECT username FROM users WHERE strpos(groups,",2,");';
$rows = $dbUser->query($sql)->fetchAll(PDO::FETCH_ASSOC);
print_r($rows);

?>
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