请用sql语句实现语文、数学、英语成绩的优良差
SQL
select stuName as 姓名,
(case when math>80 then '优' when
math<60 then '差' when math<=80 and
math>=60 then '良' end) as 数学,
(case when english>80 then '优' when
english<60 then '差' when english<=80
and english>=60 then '良' end) as 英语,
(case when chinese>80 then '优' when
chinese<60 then '差' when chinese<=80
and chinese>=60 then '良' end) as 语文
from stu_tab