MySql加入三個表

Question

我已將三個表連接到一個表中，但存在不同的列名稱但具有相同的值。

學生表

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

課程表

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

橋

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

Answer 1

假設你想加入由id領域：

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 

這裏是關於SQL joins

Answer 2

使用JOIN一些信息，以實現您的結果

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

假設您作爲主鍵上第一欄加入表格。

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

你可以使用JOIN

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