如果兩個標準的結果相同，則選擇一個值

Question

如果兩個標準的結果相同，則從CODE行中選擇值。一個條件的 示例：

DAYS = 30，RATE 2 AND DAYS = 60，評分0

表

ID | CODE| DAYS| RATE| 
    1 | 01 | 30 | 2 | 
    2 | 05 | 20 | 3 | 
    3 | 01 | 60 | 0 | 
    4 | 06 | 30 | 3 | 
... 

第一部分是

SELECT * FROM Tablename WHERE (DAYS = 30 AND RATE = 2) 

但第二部分..encaps ulated？

結果應該是01

有什麼建議？ thx提前。

Answer 1

你需要一個自聯接：

SELECT DISTINCT t1.code 
FROM Tablename t1 
INNER JOIN Tablename t2 
ON t1.code = t2.code 
WHERE t1.days = 30 AND t1.rate = 2 
AND t2.days = 60 AND t2.rate = 0 

Answer 2

試試這個，

SELECT * FROM Tablename WHERE (DAYS = 30 AND RATE = 2) OR (DAYS = 60 AND RATE = 0) 

Answer 3

SELECT DISTINCT CODE FROM Tablename 
WHERE (DAYS = 30 AND RATE = 2) 
OR (DAYS = 60 AND RATE = 0)