DELIMITER //
CREATE FUNCTION DateWeek ( date VARCHAR(8) )
RETURNS VARCHAR(8)
SQL SECURITY INVOKER
BEGIN
   DECLARE month VARCHAR(5);
   DECLARE ret VARCHAR(8);
   declare w int;
   
   set w = week(date) ;
   set month = concat(substring(date, 3,2),'.',substring(date, 5,2)) ;
   set ret = concat(month,'-', if(length(w) = 1, concat('0',w), w) );
   RETURN ret;
END; //
DELIMITER ;

drop function dateweek