SQLite3::createFunction()

(PHP 5 >= 5.3.0, PHP 7)

Registers a PHP function for use as an SQL scalar function

说明

publicSQLite3::createFunction(string $name, mixed $callback[,int $argument_count= -1[,int $flags= 0]]): bool

Registers a PHP function or user-defined function for use as an SQL scalar function for use within SQL statements.

参数

$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.

This function need to be defined as:

callback(mixed $value1[,mixed$...]): mixed

$value1

The first argument passed to the SQL function.

...

Further arguments passed to the SQL function.

$argument_count

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 SQLITE3_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

Returns TRUE upon successful creation of the function,FALSE on failure.

更新日志

范例

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")'));
?>

以上例程的输出类似于：

string(32) "098f6bcd4621d373cade4e832627b4f6"

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).