最近在创建function时，系统提示以下错误：
This function has none of DETERMINISTIC, NO SQL,
or READS SQL DATA in its declaration and binary logging is enabled(you might want to use the less s
DROP FUNCTION IF EXISTS fn_classes_teacher_num;
CREATE FUNCTION fn_classes_teacher_num(id_in varchar(20))
RETURNS INTEGER
READS SQL DATA
BEGIN
RETURN
(SELECT num_of_teacher from classes wh
