SQLite3::createAggregate

(PHP 5 >= 5.3.0, PHP 7)

SQLite3::createAggregate — Registers a PHP function for use as an SQL aggregate function

说明

public bool SQLite3::createAggregate ( string $name , mixed $step_callback , mixed $final_callback [, int $argument_count = -1 ] )

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

参数

name

Name of the SQL aggregate to be created or redefined.

step_callback

The name of a PHP function or user-defined function to apply as a callback for every item in the aggregate.

final_callback

The name of a PHP function or user-defined function to apply as a callback at the end of the aggregate data.

argument_count

The number of arguments that the SQL aggregate takes. If this parameter is negative, then the SQL aggregate may take any number of arguments.

返回值

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

User Contributed Notes

boris dot dd at gmail dot com 06-Jan-2017 04:57
<?php
class Test extends SQLite3
{
    public function __construct($file)
    {
        parent::__construct($file);
        $this->createAggregate('groupConcat', [$this, 'concatStep'], [$this, 'concatFinal']);
    }
    public function concatStep(&$context, $rowId, $string, $delimiter)
    {
        if (!isset($context)) {
            $context = [
                'delimiter' => $delimiter,
                'data'      => []
            ];
        }
        $context['data'][] = $string;
        return $context;
    }
    public function concatFinal(&$context)
    {
        return implode($context['delimiter'], $context['data']);
    }
}
$SQLite = new Test('/tmp/test.sqlite');
$SQLite->exec("create table `test` (`id` TEXT, `color` TEXT, `size` TEXT)");
$SQLite->exec("insert into `test` (`id`, `color`, `size`) values ('1', 'red', 'M')");
$SQLite->exec("insert into `test` (`id`, `color`, `size`) values ('1', 'green', 'M')");
$SQLite->exec("insert into `test` (`id`, `color`, `size`) values ('1', 'blue', 'S')");
$Result = $SQLite->query("select `size`, groupConcat(`color`, ';') as `color` from `test` group by `size`");
while ($row = $Result->fetchArray(SQLITE3_ASSOC)) {
    print_r($row);
}
/*
Array
(
    [size] => M
    [color] => red;green
)
Array
(
    [size] => S
    [color] => blue
)
*/
sukmaagungsaputra at gmail dot com 21-Feb-2015 02:09
Lacks of example, right?
Let's try to give to SQlite3 the capability like ones of MySQL's
- REGEXP operator,
- MD5 function, and
- GROUP_CONCAT aggregate function

$db = new SQLite3($filename);
$db->createFunction('regexp', function ($a,$b) { return preg_match("/$a/i", $b); });
$db->createFunction('md5', function ($a) { return md5($a); });
$db->createAggregate ('group_concat',
            function(&$context, $rownumber, $str) { $context[]=$str; return $context; },
            function(&$context) {return implode(",", (array) $context); });