連接兩個表沒有PK

Question

我有以下數據

表1

TransID | Ref_Entity | Amount 
--------+------------+-------- 
null | DEPOSIT | 0.00 
null | BANKCHARGES| 0.00 
null | OTHERS  | 0.00 

表2

TransID | Ref_Entity | Amount 
--------+------------+--------- 
1  | DEPOSIT | 100.00 
1  | BANKCHARGES| 100.00 
2  | OTHERS  | 150.00 

，並希望有這樣的輸出：

1 | DEPOSIT | 100.00 
1 | BANKCHARGES| 100.00 
1 | OTHERS  |  0.00 
2 | DEPOSIT |  0.00 
2 | BANKCHARGES|  0.00 
2 | OTHERS  | 150.00 

我試過了：

SELECT 
    * (SELECT '' AS TransID, Ref_Entity, 0.00 AS Amount 
     FROM TABLE1 
     UNION 
     SELECT TransID, Ref_Entity, Amount 
     FROM TABLE2 
    ) 

感謝您的幫助。

Answer 1

你需要得到的TransID和Ref_Entity的不同組合，然後做一個LEFT JOIN上Table2

WITH Combinations(TransID, Ref_Entity) AS(
    SELECT 
     t2.TransID, t1.Ref_Entity 
    FROM (SELECT DISTINCT Ref_Entity FROM Table1) t1 
    CROSS JOIN (SELECT DISTINCT TransID FROM Table2) t2 
) 
SELECT 
    c.TransID, 
    c.Ref_Entity, 
    Amount = ISNULL(t2.Amount, 0) 
FROM Combinations c 
LEFT JOIN Table2 t2 
    ON c.TransID = t2.TransID 
    AND c.Ref_Entity = t2.Ref_Entity; 

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