查詢鏈接4代表與INNER JOIN

Question

我有以下4個表：

student_info：

S_ID naam email telefoon locatie U_ID 
    1 Walter Walter@ 03938 Home  1 

student_combi：

S_ID V_ID 
    1 1 

student_vak：

V_ID vak R_ID 
    1 HTML 1 

student_richting：

R_ID richting 1 Web開發

我想查詢中使用INNER JOIN

選擇 'VAK'（從 'student_vak' 表）和 'richting'（從 'student_richting' 表）

到目前爲止，我有這樣的：

SELECT student_vak.vak,student_richting.richting 
FROM student_vak 
INNER JOIN student_richting ON student_vak.R_ID = student_richting.R_ID 
INNER JOIN student_combi ON student_info.S_ID = student_combi.S_ID 
INNER JOIN student_vak ON student_combi.V_ID = student_vak.V_ID 
INNER JOIN student_richting ON student_vak.R_ID = student_richting.R_ID 

謝謝你在前進，如果你知道答案。

Answer 1

以下內容將滿足您的需求。

SELECT S.S_Id Student_Id, S.Naam Student_Name, SV.vak, SR.richting 
FROM Student_Info S 
INNER JOIN Student_Combi SC ON S.S_id = SC.S_Id 
INNER JOIN Student_Vak SV ON SC.V_Id = SV.V_Id 
INNER JOIN student_richting SR ON SV.R_Id = SR.R_Id 

--Example

CREATE TABLE #student_vak 
(V_ID INT, 
vak  NVARCHAR(256), 
R_ID INT) 

INSERT INTO #student_vak 
SELECT '1', 'HTML','1' 

CREATE TABLE #student_richting 
(R_ID  INT, 
richting NVARCHAR(256) 
) 
INSERT INTO #student_richting 
SELECT '1', 'Web-Development' 

SELECT SV.vak, SR.richting 
FROM #student_vak SV 
INNER JOIN #student_richting SR ON SV.R_Id = SR.R_Id