如何删除没有唯一行id存在的重复行?
我的座位是
col1 col2 col3 col4 col5 col6 col7
john 1 1 1 1 1 1
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
sally 2 2 2 2 2 2
我想留下以下重复删除后:
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
我尝试了一些查询，但我认为他们取决于有一个行id，因为我没有得到想要的结果。例如:
DELETE
FROM table
WHERE col1 IN (
SELECT id
FROM table
GROUP BY id
HAVING (COUNT(col1) > 1)
)
当前回答
我更喜欢CTE从sql server表中删除重复的行
强烈推荐阅读本文::http://codaffection.com/sql-server-article/delete-duplicate-rows-in-sql-server/
保持原创性
WITH CTE AS
(
SELECT *,ROW_NUMBER() OVER (PARTITION BY col1,col2,col3 ORDER BY col1,col2,col3) AS RN
FROM MyTable
)
DELETE FROM CTE WHERE RN<>1
不保留原创
WITH CTE AS
(SELECT *,R=RANK() OVER (ORDER BY col1,col2,col3)
FROM MyTable)
DELETE CTE
WHERE R IN (SELECT R FROM CTE GROUP BY R HAVING COUNT(*)>1)
其他回答
如果你有能力临时添加一个列到表中，这是一个适合我的解决方案:
ALTER TABLE dbo.DUPPEDTABLE ADD RowID INT NOT NULL IDENTITY(1,1)
然后使用MIN和GROUP BY的组合执行DELETE
DELETE b
FROM dbo.DUPPEDTABLE b
WHERE b.RowID NOT IN (
SELECT MIN(RowID) AS RowID
FROM dbo.DUPPEDTABLE a WITH (NOLOCK)
GROUP BY a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE
);
验证DELETE执行正确:
SELECT a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE, COUNT(*)--MIN(RowID) AS RowID
FROM dbo.DUPPEDTABLE a WITH (NOLOCK)
GROUP BY a.ITEM_NUMBER,
a.CHARACTERISTIC,
a.INTVALUE,
a.FLOATVALUE,
a.STRINGVALUE
ORDER BY COUNT(*) DESC
结果中不应有计数大于1的行。最后，删除rowid列:
ALTER TABLE dbo.DUPPEDTABLE DROP COLUMN RowID;
我更喜欢CTE从sql server表中删除重复的行
强烈推荐阅读本文::http://codaffection.com/sql-server-article/delete-duplicate-rows-in-sql-server/
保持原创性
WITH CTE AS
(
SELECT *,ROW_NUMBER() OVER (PARTITION BY col1,col2,col3 ORDER BY col1,col2,col3) AS RN
FROM MyTable
)
DELETE FROM CTE WHERE RN<>1
不保留原创
WITH CTE AS
(SELECT *,R=RANK() OVER (ORDER BY col1,col2,col3)
FROM MyTable)
DELETE CTE
WHERE R IN (SELECT R FROM CTE GROUP BY R HAVING COUNT(*)>1)
在sql server中可以通过多种方式来实现 最简单的方法是: 将重复行表中的不同行插入到新的临时表中。然后从重复的行表中删除所有数据，然后从没有重复的临时表中插入所有数据，如下所示。
select distinct * into #tmp From table
delete from table
insert into table
select * from #tmp drop table #tmp
select * from table
使用公共表表达式(CTE)删除重复行
With CTE_Duplicates as
(select id,name , row_number()
over(partition by id,name order by id,name ) rownumber from table )
delete from CTE_Duplicates where rownumber!=1
哦，哇，我觉得准备这些答案太愚蠢了，他们就像专家的答案，包括所有的CTE和临时表等。
为了让它工作，我所做的只是使用MAX聚合ID列。
DELETE FROM table WHERE col1 IN (
SELECT MAX(id) FROM table GROUP BY id HAVING ( COUNT(col1) > 1 )
)
注意:您可能需要多次运行它来删除重复，因为这一次只会删除一组重复的行。
-- this query will keep only one instance of a duplicate record.
;WITH cte
AS (SELECT ROW_NUMBER() OVER (PARTITION BY col1, col2, col3-- based on what? --can be multiple columns
ORDER BY ( SELECT 0)) RN
FROM Mytable)
delete FROM cte
WHERE RN > 1
