如何使用SQL从多个表中删除行?
我有三张桌子:如何使用SQL从多个表中删除行?,sql,sql-server,Sql,Sql Server,我有三张桌子: mainTable: id | uniqField -------------- 1 | 1111 2 | 1111 3 | 2222 4 | 2222 5 | 3333 6 | 4444 table1: id|name|deleted ---------- 1|Mike|0 2|Mike|0 5|John|0 table2: id|name|deleted ---------- 3|Peke|0 4|Peke|0 6|Vels|0 表按id字段绑定
mainTable:
id | uniqField
--------------
1 | 1111
2 | 1111
3 | 2222
4 | 2222
5 | 3333
6 | 4444
table1:
id|name|deleted
----------
1|Mike|0
2|Mike|0
5|John|0
table2:
id|name|deleted
----------
3|Peke|0
4|Peke|0
6|Vels|0
表按id字段绑定。现在我想从这个表中删除重复项。对于
mainTable
我可以使用:
DELETE mainTable
FROM mainTable
LEFT OUTER JOIN (
SELECT MIN(id) as RowId, uniqField
FROM mainTable
GROUP BY uniqField
) as KeepRows ON
mainTable.id= KeepRows.RowId
WHERE
KeepRows.RowId IS NULL
但在表1和表2中,我想将deleted
字段设置为0->1
以重复,我的意思是:
1 | 1111
2 | 1111 -> duplicate->remove
1|Mike|0
2|Mike|0->duplicate-> 0->1
试试这个-
SET NOCOUNT ON;
DECLARE @mainTable TABLE
(
id INT,
uniqField INT
)
INSERT INTO @mainTable (id, uniqField)
VALUES (1, 1111), (2, 1111), (3, 2222), (4, 2222), (5, 3333), (6, 4444)
DECLARE @deleted TABLE (id INT)
;WITH cte AS
(
SELECT *, RowNum = ROW_NUMBER() OVER (PARTITION BY uniqField ORDER BY 1/0)
FROM @mainTable
)
DELETE FROM cte
OUTPUT DELETED.id INTO @deleted
WHERE RowNum > 1
DECLARE @table1 TABLE
(
id INT,
uniqField VARCHAR(10),
deleted BIT
)
DECLARE @table2 TABLE
(
id INT,
uniqField VARCHAR(10),
deleted BIT
)
INSERT INTO @table1 (id, uniqField, deleted)
VALUES (1, 'Mike', 0), (2, 'Mike', 0), (5, 'John', 0)
INSERT INTO @table2 (id, uniqField, deleted)
VALUES (3, 'Peke', 0), (4, 'Peke', 0), (6, 'Vels', 0)
UPDATE @table1
SET deleted = 1
FROM @deleted
WHERE [@deleted].id = [@table1].id
UPDATE @table2
SET deleted = 1
FROM @deleted
WHERE [@deleted].id = [@table2].id
SELECT * FROM @table1
SELECT * FROM @table2
输出-
id uniqField deleted
----------- ---------- -------
1 Mike 0
2 Mike 1
5 John 0
id uniqField deleted
----------- ---------- -------
3 Peke 0
4 Peke 1
6 Vels 0
这些表之间是否设置了任何
约束
?由id
字段绑定的表:mainTable.id->table1.id
,mainTable.id->table2.id
。仅此而已。它是基于SQL的约束吗?如果是这样,您可以使用试图违反约束时返回的错误来删除条目