Krzysztof Wolniak kwolniak

Method 1 - BAD

<?php

$toDelete1 = [0, 1]; // if it's for example [0, 2] so there is no problem
$list1 = new ArrayObject([0, 1, 2, 3, 4, 5, 6]);

foreach ($list1 as $key1 => $item1) {
    if (in_array($item1, $toDelete1)) {

	SELECT t1., u.
	FROM `msg` AS `t1`
	INNER JOIN
	(
	SELECT MAX(m_date) AS maxDate, m_group
	FROM msg
	WHERE (m_to_u_id=1 OR m_from_u_id=1) AND m_deleted='0'
	GROUP BY m_group
	) t2
	ON t1.m_group = t2.m_group