PDO::sqliteCreateFunction

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

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

说明

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

此函数是实验性的。此函数的表象,包括名称及其相关文档都可能在未来的 PHP 发布版本中未通知就被修改。使用本函数风险自担 。

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.

参数

function_name

The name of the function used in SQL statements.

callback

Callback function to handle the defined SQL function.

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

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.

返回值

成功时返回 TRUE, 或者在失败时返回 FALSE

更新日志

版本 说明
PHP 7.1.4 The flags has been added.

范例

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.

Tip

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

Note:

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

参见

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User Contributed Notes 1 note

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RoboTamer
5 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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