sql条件查询语句的简单实例

复制代码 代码如下:
//创建成绩表
create table result(
       stu_id varchar2(20) not null,
       china number(9,2) null,
       math number(9,2) null,
       english number(9,2) null
);

//插入数据
insert into result values('0001',60,20,80);
insert into result values('0002',80,60,80);
insert into result values('0003',20,85,80);
select *from result;

//条件查询
select  stu_id,(case
         when china>80 then '优秀'
         when china>=60 then '及格'
         when china<60 then  '不及格'
         end) as 语文 ,
      (case
         when math>80 then '优秀'
         when math>=60 then '及格'
         when math<60 then '不及格'
       end )as 数学 ,
         (case
         when english>80 then '优秀'
         when english>=60 then '及格'
         when english<60 then '不及格'
       end) as 英语
from result