1. If there is an ID field, it is a unique field
Copy Code code as follows:
Delect table where ID not in (
Select Max (ID) from table GROUP by col1,col2,col3 ...
)
The field followed by the GROUP BY clause is the condition that you use to determine the repetition, such as only col1, so as long as the content of the Col1 field is the same as that of the record.
2. If you're judging all the fields, you can do this.
Copy Code code as follows:
SELECT * into #aa from table group by Id1,id2,....
Delete Table
INSERT INTO table
SELECT * FROM #aa
3. Absence of ID
Copy Code code as follows:
Select Identity (int,1,1) as id,* into #temp from tabel
Delect # where ID not in (
Select Max (ID) from # Group by col1,col2,col3 ...)
Delect table
Inset into table (...)
Select ... from #temp
4. col1+ ', ' +col2+ ', ' ... col5 Union primary key
Copy Code code as follows:
SELECT * FROM table where col1+ ', ' +col2+ ', ' ... col5 in (
Select Max (col1+ ', ' +col2+ ', ' ... col5 ') from table
Where has count (*) >1
GROUP BY Col1,col2,col3,col4
)
The field followed by the GROUP BY clause is the condition that you use to determine the repetition, such as only col1, so as long as the content of the Col1 field is the same as that of the record.
5.
Copy Code code as follows:
Select Identity (int,1,1) as id,* into #temp from tabel
SELECT * from #temp where ID in (
Select Max (ID) from #emp where has count (*) >1 GROUP by col1,col2,col3 ...)
6.
Copy Code code as follows:
SELECT DISTINCT * into #temp tablename
Delete TableName
Go
Insert TableName SELECT * FROM #temp sqlclub
Go
drop table #temp
The above is a description of how SQL Server deletes duplicate rows.
