MySQL 存储过程中执行动态SQL语句的方法

drop PROCEDURE if exists my_procedure;
create PROCEDURE my_procedure()
BEGIN
 declare my_sqll varchar(500);
 set my_sqll='select * from aa_list';
set @ms=my_sqll;
PREPARE s1 from @ms;
EXECUTE s1;
deallocate prepare s1;
end;