DELIMITER $$
USE `t_girl`$$
DROP FUNCTION IF EXISTS `weekofmonth`$$
CREATE DEFINER=`root`@`localhost` FUNCTION `weekofmonth`(
    f_datetime DATETIME
    ) RETURNS INT(11)
BEGIN
   -- Created by ytt.
    DECLARE v_result INT;   
    DECLARE v_weekno INT;
    SET v_weekno =
    CASE DAYOFWEEK(f_datetime)
    WHEN 1 THEN 7
    WHEN 2 THEN 1
    WHEN 3 THEN 2
    WHEN 4 THEN 3
    WHEN 5 THEN 4
    WHEN 6 THEN 5
    WHEN 7 THEN 6
    END;
    SET v_result = CEIL(DAYOFMONTH(DATE_SUB(f_datetime,INTERVAL v_weekno DAY))/7)+1;
    RETURN v_result;
    END$$
DELIMITER ;