MySql联接三个表

Question

我已将三个表连接到一个表中，但列名不同但值相同。

学生桌

-------------
CV_id    name
-------------
LC001     ali
LC002     ahmed
LC003     john
LC004     king

课程表

-------------
Us_id    name
-------------
LC001     physic
LC002     maths
LC003     computer
LC004     chemistry

桥

-------------
sid    CV_cid
-------------
ti     LC001
ni     LC002
df     LC003
ed     LC004

Answer 1

假设您想通过id字段加入：

select s.name student_name, c.name course_name, b.sid from student s
join course c
on c.us_id = s.cv_id
join bridge b
on b.cv_id = s.cv_id

这是有关SQL连接的一些信息

Answer 2

使用JOIN实现您的结果

SELECT ST.CV_id, ST.name, CO.name, BR.`sid`
FROM Student ST
INNER JOIN Course CO ON CO.Us_id = ST.CV_id
INNER JOIN Bridge BR ON BR.CV_cid = ST.CV_id

Answer 3

假设您将第一列的表作为主键。

SELECT t1.col, t2.col, t3.col FROM tbl1 join tbl2 ON tbl1.pk = tbl2.pk join tbl3 ON tbl2.pk = tbl3.pk

Answer 4

您可以使用加入

SELECT s.CV_id, s.name, c.name, b.sid
FROM Student s
INNER JOIN Course c ON c.Us_id = s.CV_id
INNER JOIN Bridge b ON b.CV_cid = s.CV_id