Rsa97

SELECT `e1`.`user2` FROM `event` AS `e1`
    INNER JOIN `event` AS `e2` ON `e1`.`user2` = `e2`.`user1`
    WHERE `e1`.`user1` = $user AND `e2`.`user2` = $user

SELECT `e1`.`user1`, `e1`.`user2` FROM `event` AS `e1`
    INNER JOIN `event` AS `e2` ON `e1`.`user2` = `e2`.`user1` AND `e1`.`user1` = `e2`.`user2`
    WHERE `e1`.`user1` < `e1`.`user2`

$sql = "UPDATE indexing_link SET title='".$title."', short='".$short ."' WHERE id=".$id_current_url;
print $sql;
mysqli_query($mysqli, $sql) or die('Error_ ('.mysqli_errno($mysqli).') '.mysqli_error($mysqli));

SET @a := 0;
SET @b := 0;
SELECT * FROM (
  SELECT @a := @a+1 as `num`, `id`, `cat` FROM `stock` WHERE `cat` = 1
  UNION SELECT @b := @b+1 as `num`, `id`, `cat` FROM `stock` WHERE `cat` = 2) AS `tbl`
  ORDER BY `num`, `cat`;

SELECT DISTINCT `res`.`id_page` FROM `fields_value` AS `res`
  INNER JOIN `fields_value` AS `f1` ON (`f1`.`id_page` = `res`.`id_page` AND `f1`.`id_field` = 22 AND `f1`.`value` = 'Платный')
  INNER JOIN `fields_value` AS `f2` ON (`f2`.`id_page` = `res`.`id_page` AND `f2`.`id_field` = 11 AND `f2`.`value` = '100')
  INNER JOIN `fields_value` AS `f3` ON (`f3`.`id_page` = `res`.`id_page` AND `f3`.`id_field` = 33 AND `f3`.`value` = 'есть')

SELECT `id_услуги`, COUNT(`id услуги`) 
    FROM `услуги` 
    WHERE `id_отеля` IN (список отелей) 
    GROUP BY `id_услуги`

SELECT `услуги`.`id_услуги`, COUNT(`услуги`.`id услуги`) 
    FROM `услуги` 
        RIGHT JOIN `отели` ON `отели`.`id_отеля` = `услуги`.`id_отеля`
    WHERE условия выбора отеля
    GROUP BY `услуги`.`id_услуги`