wuzhicheng123456的专栏

case when   用sum而不是count select sum(case when score<60 then 1 else null end) bujige, sum(case when score>=60 and score<80 then 1 else null end) jige, sum(case when score>=80 then 1 el...

关键字：procedure drop procedure if exists pp;/*如果存在存储过程pp则删除pp*/ delimiter //  /**设置以//为sql语句结尾*/ 1:不带参数的存储过程 create procedure pp() begin select count(*) from t_com_dim_date; end//