所有数学课程成绩 大于 语文课程成绩的学生的学号

CREATE TABLE course (
id int,
sid int ,
course string,
score int
) ;

// 插入数据
// 字段解释：id, 学号， 课程， 成绩
INSERT INTO course VALUES (1, 1, ‘yuwen‘, 43);
INSERT INTO course VALUES (2, 1, ‘shuxue‘, 55);
INSERT INTO course VALUES (3, 2, ‘yuwen‘, 77);
INSERT INTO course VALUES (4, 2, ‘shuxue‘, 88);
INSERT INTO course VALUES (5, 3, ‘yuwen‘, 98);
INSERT INTO course VALUES (6, 3, ‘shuxue‘, 65);

求：所有数学课程成绩 大于 语文课程成绩的学生的学号

select sid,case when course="yuwen" then score else 0 end as yuwen,
case when course="shuxue" then score else 0 end as shuxue
from course;

1 43 0
1 0 55
2 77 0
2 0 88
3 98 0
3 0 65
select tmp.sid,Max(tmp.yuwen) as yuwen,max(tmp.shuxue) as shuxue
from(
select sid,case when course="yuwen" then score else 0 end as yuwen,
case when course="shuxue" then score else 0 end as shuxue
from course
) tmp
group by tmp.sid;

1 43 55
2 77 88
3 98 65
select stmp.sid
from (
select tmp.sid,Max(tmp.yuwen) as yuwen,max(tmp.shuxue) as shuxue
from(
select sid,case when course="yuwen" then score else 0 end as yuwen,
case when course="shuxue" then score else 0 end as shuxue
from course
) tmp
group by tmp.sid
) stmp where stmp.shuxue > stmp.yuwen;

所有数学课程成绩 大于 语文课程成绩的学生的学号

原文：http://blog.51cto.com/6000734/2321019