SQL服務器自參照查詢

Question

請考慮以下幾點：

CREATE DATABASE TEST 
USE TEST 

CREATE TABLE Student 
    (
     StudentID INT IDENTITY 
        PRIMARY KEY , 
     FirstName NVARCHAR(50) , 
     LastName NVARCHAR(50) 
    ) 

CREATE TABLE StudentComponent 
    (
     StudentComponentID INT IDENTITY 
          PRIMARY KEY , 
     StudentID INT FOREIGN KEY REFERENCES dbo.Student(StudentID) , 
     ComponentName NVARCHAR(50) , 
     ComponentRef NVARCHAR(50) , 
     ComponentType NCHAR(2) 
    ) 

CREATE TABLE Component 
    (
     ComponentID INT IDENTITY 
         PRIMARY KEY , 
     StudentComponentID INT FOREIGN KEY REFERENCES dbo.StudentComponent(StudentComponentID) , 
     ComponentName NVARCHAR(50) , 
     ComponentRef NVARCHAR(50) , 
     ComponentType NCHAR(2) 
    ) 

我有3個表

1. 學生
2. StudentComponent
3. 組件

拆分爲三個維度

CREATE TABLE DimClass 
    (ClassDwKey INT, 
    ClassName NVARCHAR(50), 
    ClassRef NVARCHAR(50)) 

    CREATE TABLE DimCollege 
    (CollegeDwKey INT, 
    CollegeName NVARCHAR(50), 
    CollegeRef NVARCHAR(50)) 

    CREATE TABLE DimSubject 
    (SubjectDwKey INT, 
    SubjectName NVARCHAR(50), 
    SubjectRef NVARCHAR(50)) 

    CREATE TABLE DimStudent 
    (StudentDwKey INT, 
    StudentName NVARCHAR(50)) 

    INSERT INTO 

    CREATE TABLE FactAcademicEvent 
    (StudentDwKey int, ClassDwKey int, CollegeDwKey int, SubjectDwKey INT) 

它們之間的關係相同（學生 - >學生組件 - >組件）。我已經將組件分成了它們自己的維度，DimClass，DimCollege，DimSubject（由componenttype字段拆分，='CL'爲類，'SU'爲主題，'CO'爲大學等我試圖加載一個事實表從我的維度獲得我的代理鍵並生成以下行：

StudentDwKey（來自dimstudent），ClassDwKey，CollegeDwKey，SubjectDwKey。維與組件表之間存在關聯，ComponentKey通過學生組件錶鏈接到學生。

StudentComponent和組件基本上是相同的，除了StudentComponent引用學生，讓有更多的行。

任何想法？

Answer 1

編輯：

完全改變基於OP的編輯和評論。

SELECT 
    s.StudentID, 
    MAX(dim_s.StudentDwKey) AS StudentDwKey, 
    MAX(dim_cl.ClassDwKey ) AS ClassDwKey, 
    MAX(dim_su.SubjectDwKey) AS SubjectDwKey, 
    MAX(dim_co.CollegeDwKey) AS CollegeDwKey 
FROM 
    Student   AS s 
LEFT JOIN 
    StudentComponent AS sc 
    ON sc.StudentID = s.StudentID 
LEFT JOIN 
    dimStudent   AS dim_s 
    ON dim_s.StudentName = s.StudentName -- or whatever is a reliable join 
LEFT JOIN 
    dimClass   AS dim_cl 
    ON dim_cl.ClassRef = sc.ComponentRef 
    AND sc.ComponentType = 'CL' 
LEFT JOIN 
    dimSubject   AS dim_su 
    ON dim_su.SubjectRef = sc.ComponentRef 
    AND su.ComponentType = 'SU' 
LEFT JOIN 
    dimCollege   AS dim_co 
    ON dim_co.CollegeRef = sc.ComponentRef 
    AND sc.ComponentType = 'CO' 
GROUP BY 
    s.StudentID 

Answer 2

請學生表中的學生的詳細信息（您已完成）和組件的詳細信息在組件表（你沒有這樣做），並使用StudentComponent表將它們連接在一起。事情是這樣的：

CREATE DATABASE TEST 
USE TEST 

CREATE TABLE Student 
    (
     StudentID INT IDENTITY 
        PRIMARY KEY , 
     FirstName NVARCHAR(50) , 
     LastName NVARCHAR(50) 
    ) 

CREATE TABLE StudentComponent 
    (
     StudentComponentID INT IDENTITY 
          PRIMARY KEY , 
     StudentID INT FOREIGN KEY REFERENCES dbo.Student(StudentID) , 
     ComponentID INT FOREIGN KEY REFERENCES dbo.Component(ComponentID), 
    ) 

CREATE TABLE Component 
    (
     ComponentID INT IDENTITY 
         PRIMARY KEY , 
     ComponentName NVARCHAR(50) , 
     ComponentRef NVARCHAR(50) , 
     ComponentType NCHAR(2) 
    )