如何消除和仅显示非重复记录

Question

见下表：

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

现在我想只显示非重复记录。这意味着3,5,7。

如何编写查询以获得结果？

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（*）as cnt，col1，col2 从表 GROUP BY col2 有cnt = 1;

Answer 4

相信这是清楚和正确的：

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