選擇具有相同編號但不同於其他列的值

Question

我有這張表。

擁有：

Pid Cid 
100 1 
100 2 
200 1 
200 3 
300 4 
400 1 
400 4 
400 5 
500 2 
500 4 

，我需要選擇PID僅適用於誰擁有CID = 1而不是CID = 2 輸出應該是：

pid 
200 
400 

我的查詢是：

SELECT Pid 
FROM OWNS 
WHERE Cid = 1 and Cid <> 2 

，但我得到的結果：

pid 
100 
200 
400 

Answer 1

嘗試

SELECT distinct Pid 
FROM OWNS 
WHERE 
    Pid not in (select Pid from OWNS where Cid = 2) 
AND CID = 1; 

Answer 2

或者這樣：

SELECT `pid` 
FROM `OWNS` 
WHERE `cid` = '1' 
    AND `pid` in (SELECT `pid` 
        FROM `OWNS` 
        WHERE `cid` != '1' AND `cid` != '2')