访问 SQL 子查询或关联数组语句

Question

Field1 Field2 Field3
A      1      D         'should be dropped
A      1      K         'should be dropped
B      1      K
B      2      K
A      1      P         'should be dropped
A      2      P
A      1      M         'should be dropped  

如果字段 3 = D，则无论字段 3 值如何，都应排除任何("A"1"(组合。因此，在此示例中，不应返回前两条记录。

Answer 1

所以你有一个现有的查询(我们称之为[TheThirdQuery](，它返回

Field1  Field2  Field3  comment
------  ------  ------  -----------------
A            1  D       should be dropped
A            1  K       should be dropped
B            1  K
B            2  K
A            1  P       should be dropped
A            2  P
A            1  M       should be dropped

如果您想要一个将省略 [comment] 列中指示的行的查询(不使用 [comment] 列本身(，则该查询将是

SELECT * FROM TheThirdQuery t1 
WHERE NOT EXISTS (
    SELECT * FROM TheThirdQuery t2 
    WHERE t2.Field1=t1.Field1 
        AND t2.Field2=t1.Field2 
        AND t2.Field3='D'
    )