如何消除並只顯示非重複記錄

Question

參見下表：

col1  col2 
----  ---- 
1 | a  
2 | b  
3 | c 
4 | a 
5 | d 
6 | b 
7 | e 

現在我想只顯示非重複記錄。這意味着3,5,7。

如何編寫查詢來獲得結果？

Answer 1

SELECT col1, col2 
FROM table 
GROUP BY col2 
HAVING COUNT(*) = 1; 

Answer 2

SELECT B.* 
FROM 
(
SELECT col2 
FROM YOURTABLE 
GROUP BY col2 
HAVING COUNT(*)=1 
) A, 
YOURTABLE B 
WHERE A.col2 = B.col2 

Answer 3

SELECT COUNT（*）作爲CNT，COL1，COL2 FROM表 GROUP BY COL2 HAVING CNT = 1;

Answer 4

相信這是明確的，相當正確的：

SELECT * 
FROM table 
WHERE 
    col2 IN (SELECT col2 FROM table GROUP BY col2 HAVING COUNT(*) = 1)