SQL filter, delete, duplicate record statement in table

This article describes the SQL name for filtering duplicate records using a having group by and various select in federated queries to implement a variety of different methods.
-
1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to judge

The code is as follows
SELECT * FROM arranges
where Peopleid in (select Peopleid from arranges group by Peopleid has count (Peopleid) > 1)

2, delete redundant records in the table, duplicate records are based on a single field (Peopleid) to judge, leaving only rowid minimal records

The code is as follows
Delete from arranges
where Peopleid in (select Peopleid from arranges group by Peopleid has count (Peopleid) > 1)
and rowID not in (select Min. rowid from arranges group by Peopleid have Count (Peopleid) >1)

3. Find redundant records in the table (multiple fields)

The code is as follows
SELECT * FROM Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROUP by PEOPLEID,SEQ have count (*) > 1)

4, delete redundant records in the table (multiple fields), leaving only the smallest ROWID records

The code is as follows
Delete from Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROUP by PEOPLEID,SEQ have count (*) > 1)
and rowID not in (select Min. rowid from vitae GROUP by PEOPLEID,SEQ have Count (*) >1)

5, look for redundant records in the table (multiple fields), does not contain the smallest ROWID records

The code is as follows
SELECT * FROM Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROUP by PEOPLEID,SEQ have count (*) > 1)
and rowID not in (select Min. rowid from vitae GROUP by PEOPLEID,SEQ have Count (*) >1)

Two)
For
There is a field "name" in Table A,
and the "name" value may be the same between different records,
Now you need to query the records in the table, the "name" value duplicates the item;

The code is as follows
Select Name,count (*) from-A Group by Name has Count (*) > 1

If the same gender is also the same large as the following:

The code is as follows
Select Name,sex,count (*) from-A Group by Name,sex have Count (*) > 1

Three)
Method One

The 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 duplicates of the record, one is a completely duplicate record, that is, all the fields are duplicate records, the second is some key fields duplicate records, such as the Name field repeats, and other fields do not necessarily repeat or repeat can be ignored.

1, for the first duplication, easier to solve, using

The code is as follows
SELECT DISTINCT * FROM tablename

You can get a result set without duplicate records.

If the table needs to delete duplicate records (1 for Duplicate records), you can delete them as follows

The code is as follows
SELECT DISTINCT * into #Tmp tablename
DROP TABLE TableName
SELECT * INTO TableName from #Tmp
drop table #Tmp

This duplication occurs because the table is poorly designed and can be resolved by adding a unique index column.

2. This type of repetition usually requires the first record in the duplicate record to be retained, as follows

Suppose there is a duplicate field of name,address that requires a unique result set for both fields

The 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 in (select Autoid from #tmp2)

The last select gets the name,address result set (but one more autoid field, which can be written in the SELECT clause to omit this column)

(iv) Duplication of enquiries

The code is as follows
SELECT * FROM tablename where ID in (
Select ID from tablename
GROUP BY ID
Having count (ID) > 1
)