Teach you several ways to remove duplicate data in SQL Server

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Method One

Copy CodeThe code is as follows:
Declare @max integer, @id integer
Declare cur_rows cursor Local for select main field, COUNT (*) from table name Group by main field having count (*) > 1
Open Cur_rows
Fetch cur_rows into @id, @max
While @ @fetch_status =0
Begin
Select @max = @max-1
SET ROWCOUNT @max
Delete from table name where main field = @id
Fetch cur_rows into @id, @max
End
Close Cur_rows
SET ROWCOUNT 0

Method Two
There are two meanings of duplicate records, one is a completely duplicate record, that is, all fields are duplicated records, and the second is some key field duplicate records, such as the Name field repeats, and other fields may not be repeated or can be ignored.
1, for the first kind of repetition, easier to solve, using

Copy CodeThe code is as follows:
SELECT DISTINCT * from TableName

You can get a result set with no duplicate records.
If the table needs to delete duplicate records (duplicate records retain 1), you can delete them as follows

Copy CodeThe code is as follows:
SELECT DISTINCT * to #Tmp from TableName
drop table TableName
SELECT * Into TableName from #Tmp
drop table #Tmp

This duplication occurs because the table is poorly designed and the unique index columns are added to resolve.
2, this kind of repetition problem usually requires to keep the first record in the duplicate record, the operation method is as follows
Suppose there is a duplicate field name,address, which requires the result set to be unique for both fields

Copy CodeThe code is as follows:
Select Identity (int,1,1) as Autoid, * into #Tmp from TableName
Select min (autoid) as autoid into #Tmp2 from #Tmp Group by name,autoid
SELECT * from #Tmp where autoid on (select Autoid from #tmp2)

The last select is the result set that name,address not duplicate (but one more autoid field, which can be written in the SELECT clause without this column in the actual write)

Some time ago wrote how to delete duplicate records in SQL database is for SQL database, recently found that someone needs Access database to delete duplicate records of the statement, sent up to share with you.

Copy CodeThe code is as follows:
Delete from table name where duplicate field name in (Select repeating field name from table name Group by repeating field name having count (repeating field name) > 1) and ID not in (select min (i d) from table name Group by repeating field name having count (repeating field name) >1)

Teach you several ways to delete duplicate data in SQL Server (GO)