我与表的数据库:这是连接表来获取数据的正确方法吗?
Student(SID,Name,Surname,Age)
Registration(StudentID,CourseID)
Course(CID,Name,Cost)
我想提取与学生的课程超过20个年轻下面的查询做到这一点只有名字?
SELECT C.NAME
FROM Course C
INNER JOIN Registration
INNER JOIN Student S
WHERE CID = CourseID
AND SID = StudentID
AND Age < 20
GROUP BY C.NAME
我也想提取学生每门课程让学生比20年轻的数量是否正确,如下办呢?
SELECT count(S.NAME)
,C.NAME
FROM Student S
INNER JOIN Course C
INNER JOIN Registration
WHERE Age < 20
AND CID = CourseID
AND SID = StudentID
GROUP BY C.NAME
你用什么db? Mysql还是SQL?有两个sintax之间的区别 –
@LelioFaieta你可以给我一个链接到'SQL'数据库吗?我很好奇它与MySQL的区别。 –
@ Lelio - post被标记为MySQL .... – MuppetGrinder