区分表

Question

我有以下表格;

 A   B                       A   B
 _____                       _____
 1   t                       7   a
 2   r                       5   d
 3   e                       3   e
 4   f
 5   d
 6   s
 7   a

而且，输出应该是;

 A   B                     
 _____                     
 1   t                      
 2   r                     

 4   f

 6   s

换句话说，我想要这两个表的区别。我希望this figure中的区域A. 我怎么能这样做？

Answer 1

试试这个：

SELECT t1.*
FROM t1
LEFT JOIN t2 USING (A, B)
WHERE t2.A IS NULL

Answer 2

不使用JOIN

SELECT A, B
FROM tableA
WHERE A NOT IN
    (SELECT Distinct A FROM tableB)

Answer 3

这应该可以解决问题：

SELECT 
    A, 
    B 
FROM Table_1
WHERE NOT EXISTS 
    (
        SELECT Table_2.A AS Test
        FROM Table_2 
        INNER JOIN Table_1 AS T ON Table_2.A = Table_1.A
    )

Answer 4

SELECT A, B 
  FROM Table1
EXCEPT
SELECT A, B 
  FROM Table2;