我有三个表名为
**Student Table** ------------- id name ------------- 1 ali 2 ahmed 3 john 4 king **Course Table** ------------- id name ------------- 1 physic 2 maths 3 computer 4 chemistry **Bridge** ------------- sid cid ------------- 1 1 1 2 1 3 1 4 2 1 2 2 3 3 3 4 4 1 4 2
现在要显示学生姓名和他所学习的课程名称,
**Result** --------------------------- Student Course --------------------------- ahmed physic ahmed maths ahmed computer ahmed chemistry ali physic ali maths john computer john chemistry king physic king maths
我建立以下查询
select s.name as Student, c.name as Course from student s, course c join bridge b on c.id = b.cid order by s.name
但是它不会返回所需的结果…
如果我想找到谁是其他经理,那么归一化表格将是什么:
**employee** ------------------- id name ------------------- 1 ali 2 king 3 mak 4 sam 5 jon **manage** -------------- mid eid -------------- 1 2 1 3 3 4 4 5
并希望得到以下结果:
**result** -------------------- Manager Staff -------------------- ali king ali mak mak sam sam jon
只需使用:
select s.name "Student", c.name "Course" from student s, bridge b, course c where b.sid = s.sid and b.cid = c.cid