SQL中的条件删除？

Question

请参见下面的SQL表：

+------------+---------+
|  Category  | RevCode |
+------------+---------+
| 100.10.10  |       2 |
| 100.10.10  |       3 |
| 100.50.10  |       2 |
| 100.50.15  |       2 |
| 100.50.15  |       3 |
| 1000.80.10 |       3 |
| 200.10.10  |       3 |
| 200.50.10  |       3 |
| 200.80.10  |       3 |
| 2000.20.10 |       2 |
| 2000.20.10 |       3 |
| 2000.20.20 |       2 |
| 2000.20.20 |       3 |
| 2000.20.30 |       2 |
+------------+---------+

在满足以下条件的情况下，如何删除Rev Code为3的所有订单项：
类别的Rev Code为'2'和'3'。

例如：

+-----------+---------+
| Category  | RevCode |
+-----------+---------+
| 100.10.10 |       2 |
| 100.10.10 |       3 |
+-----------+---------+

上表将变为：

+-----------+---------+
| Category  | RevCode |
+-----------+---------+
| 100.10.10 |       2 |
+-----------+---------+

Answer 1

您可以将sub_query与having子句一起使用，如下所示：

delete from del_table
where RevCode = '3' 
  and  Category  in 
    (select Category from del_table 
     where RevCode in ('2','3')
     group by Category 
     having count(distinct RevCode) =2 )

该语句可能效率不高，可以使用exist子句代替in子句。

感谢Charlesliam的评论。 我用sql fiddle测试了以下两种情况。

情况1 ：

create table del_table(Category varchar(20),RevCode Int);
INSERT INTO  del_table VALUES 
('100.10.10',2 ),
('100.10.10',3 ),
('100.50.10',2 ),
('100.50.15',3 )

result after deletion:
CATEGORY    REVCODE
100.10.10   2
100.50.10   2
100.50.15   3

case2（一个类别有多于两行，具有相同的RevCode）：

create table del_table(Category varchar(20),RevCode Int);
INSERT INTO  del_table VALUES 
('100.10.10',2 ),
('100.10.10',2 ),
('100.10.10',3 ),
('100.10.10',3 ),
('100.50.10',2 ),
('100.50.15',3 )

result after deletion:
CATEGORY    REVCODE
100.10.10   2
100.10.10   2
100.50.10   2
100.50.15   3

Answer 2

看看这是否对您有帮助。

DECLARE @A TABLE (ID INT IDENTITY(1,1) PRIMARY KEY, CATEGORY VARCHAR(20),REVCODE INT)
INSERT INTO @A VALUES 
('100.10.10',2 ),
('100.10.10',3 ),
('100.50.10',2 ),
('100.50.15',2 ),
('100.50.15',3 ),
('1000.80.10',3),
('200.10.10',3 ),
('200.50.10',3 ),
('200.80.10',3 ),
('2000.20.10',2),
('2000.20.10',3),
('2000.20.20',2),
('2000.20.20',3),
('2000.20.30',2)

SELECT * FROM @A

表：

查询：

DELETE  LU
FROM    (
        SELECT  *,
                ROW_NUMBER() OVER (PARTITION BY CATEGORY ORDER BY REVCODE) ROW 
        FROM    @A A
        WHERE   A.REVCODE IN (2,3)
        ) LU
WHERE   LU.ROW = 2

SELECT * FROM @A

结果：