SQLite3::createFunction
(PHP 5 >= 5.3.0)
SQLite3::createFunction — Registers a PHP function for use as an SQL scalar function
Описание
$name
, mixed $callback
[, int $argument_count = -1
] )Registers a PHP function or user-defined function for use as an SQL scalar function for use within SQL statements.
Список параметров
-
name -
Name of the SQL function to be created or redefined.
-
callback -
The name of a PHP function or user-defined function to apply as a callback, defining the behavior of the SQL function.
-
argument_count -
The number of arguments that the SQL function takes. If this parameter is negative, then the SQL function may take any number of arguments.
Возвращаемые значения
Returns TRUE upon successful creation of the function, FALSE on failure.
Примеры
Пример #1 SQLite3::createFunction() example
<?php
function my_udf_md5($string) {
return md5($string);
}
$db = new SQLite3('mysqlitedb.db');
$db->createFunction('my_udf_md5', 'my_udf_md5');
var_dump($db->querySingle('SELECT my_udf_md5("test")'));
?>
Результатом выполнения данного примера будет что-то подобное:
string(32) "098f6bcd4621d373cade4e832627b4f6"
- PHP Руководство
- Функции по категориям
- Индекс функций
- Справочник функций
- Расширения для работы с базами данных
- Расширения для работы с базами данных отдельных производителей
- SQLite3
- Функция SQLite3::busyTimeout() - Sets the busy connection handler
- SQLite3::changes
- Функция SQLite3::close() - Closes the database connection
- Функция SQLite3::__construct() - Instantiates an SQLite3 object and opens an SQLite 3 database
- Функция SQLite3::createAggregate() - Registers a PHP function for use as an SQL aggregate function
- Функция SQLite3::createCollation() - Registers a PHP function for use as an SQL collating function
- Функция SQLite3::createFunction() - Registers a PHP function for use as an SQL scalar function
- SQLite3::enableExceptions
- Функция SQLite3::escapeString() - Returns a string that has been properly escaped
- Функция SQLite3::exec() - Executes a result-less query against a given database
- Функция SQLite3::lastErrorCode() - Returns the numeric result code of the most recent failed SQLite request
- Функция SQLite3::lastErrorMsg() - Returns English text describing the most recent failed SQLite request
- Функция SQLite3::lastInsertRowID() - Returns the row ID of the most recent INSERT into the database
- Функция SQLite3::loadExtension() - Attempts to load an SQLite extension library
- Функция SQLite3::open() - Opens an SQLite database
- SQLite3::openBlob
- Функция SQLite3::prepare() - Подготавливает SQL-запрос для выполнения
- Функция SQLite3::query() - Выполняет SQL-запрос
- Функция SQLite3::querySingle() - Executes a query and returns a single result
- Функция SQLite3::version() - Returns the SQLite3 library version as a string constant and as a number
Коментарии
Since regular expression is not supported by default SQLite, we can create a user function to do the job.
<?php
$db = new SQLite3("database.sqlit3", 0666);
// create a function named "preg_match"
// with the php core function "preg_match"
if ($db->createFunction("preg_match", "preg_match", 2) === FALSE)
exit("Failed creating function\n");
// this query will then works as expected
$result = $db->query("SELECT * FROM table1 WHERE
preg_match('/^(apple|orange)$/', variable1)");
?>
In PHP 5.4 there will be a createCollation method to use your custom collation method, to be able to sort datasets using unicode, like this:
<?php
setlocale(LC_COLLATE, 'fr_FR.UTF-8');
$db->createCollation('PHP_COLLATE', 'strcoll');
$db->query('SELECT * FROM my_table ORDER BY name COLLATE PHP_COLLATE;');
?>
But until this cool feature becomes available, you'll have to do some tricks, like this for french:
<?php
function sqlite3_to_ascii($str, $charset = 'UTF-8')
{
// Don't process empty strings
if (!trim($str))
return $str;
// We only process non-ascii strings
if (preg_match('!^[[:ascii:]]+$!', $str))
return $str;
$str = htmlentities($str, ENT_NOQUOTES, $charset);
$str = preg_replace('#&([A-za-z])(?:acute|cedil|circ|grave|orn|ring|slash|th|tilde|uml);#', '\1', $str);
$str = preg_replace('#&([A-za-z]{2})(?:lig);#', '\1', $str);
$str = preg_replace('#&[^;]+;#', '', $str);
return $str;
}
$db->createFunction('to_ascii', 'sqlite3_to_ascii', 1);
$res = $db->query('SELECT * FROM test ORDER BY to_ascii(text);');
?>
This will convert non-ascii characters to ascii ones before collation. In fact this won't work with non-latin languages, but for latin-languages it's better than nothing.
Please note that this will slow down about 1.8 times the query (tested on a 10.000 rows table).