加入來自同一個表的兩個查詢 - SELECT DISTINCT？

Question

我有兩個表連接AUTO_KEY字段，我從一個表中檢索數字（id），從另一個我通過數字（id）獲得多個狀態，每個狀態都有一個與其關聯的日期。 我需要限制的結果只能爲所有編號（ID）的最大/最新日期和對應的狀態

SELECT 
    OPERATION.NUMBER, 
    STATUS.STATUS, 
    Max(STATUS.DATE) 

FROM 
    STATUS, 
    OPERATION 

WHERE 
OPERATION.AUTO_KEY = STATUS.AUTO_KEY 

從這裏

Number Status Date 
----------------------------- 
1  A  10/20/13 
1  B  10/15/13 
2  A  10/10/13 
2  AX  10/05/13 
2  AD  10/03/13 
3  DD  10/03/13 

結果應該是

Number Status Date 
----------------------------- 
1  A  10/20/13 
2  A  10/10/13 
3  DD  10/03/13 

在此先感謝

Answer 1

您可以使用CTE與ROW_NUMBER()功能。也請使用Table JOIN代替FROM STATUS, OPERATION

;With CTE AS (
    SELECT O.NUMBER, S.STATUS, S.DATE, 
      ROW_NUMBER() OVER (ORDER BY S.DATE DESC) RN 
    FROM STATUS S JOIN OPERATION O 
      ON O.AUTO_KEY = S.AUTO_KEY 
) 
SELECT NUMBER, STATUS, DATE 
FROM CTE 
WHERE RN = 1 
ORDER BY NUMBER 

Answer 2

SELECT OPERATION.CNUMBER, 
     STATUS.STATUS, 
     STATUS.CDATE 
FROM STATUS, 
    OPERATION 
WHERE OPERATION.AUTO_KEY = STATUS.AUTO_KEY 
AND STATUS.CDATE = (
SELECT MAX(STATUS.CDATE) MAX_DATE 
FROM STATUS, 
     OPERATION 
WHERE OPERATION.AUTO_KEY = STATUS.AUTO_KEY 
GROUP BY OPERATION.CNUMBER)