Database Query Duplicate data

Ways to query and delete duplicate records
A
1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to determine
SELECT * from People
where Peopleid in (select Peopleid from People GROUP by Peopleid have count (Peopleid) > 1)

2, delete redundant records in the table, duplicate records are based on a single field (Peopleid) to judge, leaving only the smallest ROWID records
Delete from people
where Peopleid in (select Peopleid from People GROUP by Peopleid have count (Peopleid) > 1)
and rowID not in (select min (rowid) from people GROUP by Peopleid have Count (Peopleid) >1)

3 duplicate records in lookup table (multiple fields)
Select * from Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROUP by PE Opleid,seq having Count (*) > 1)

4, deleting extra duplicate records (multiple fields) in a table, leaving only the ROWID minimum record
Delete from Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vita E GROUP BY PEOPLEID,SEQ have count (*) > 1)
and rowID not in (select min (rowid) from Vitae Group by Peopleid,seq H aving Count (*) >1)

5, lookup table redundant duplicate records (multiple fields), does not contain ROWID minimum records
SELECT * from Vitae a
where (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vit AE GROUP BY PEOPLEID,SEQ have count (*) > 1)
and rowID not in (select min (rowid) from Vitae GROUP by Peopleid,seq Having Count (*) >1)

Two
Say
There is a field "name" in the a table,
And the "name" values between the different records are likely to be the same,
Now is the need to query out the records in the table, "name" values there are duplicates;
Select Name,count (*) from A Group by Name have Count (*) > 1

If you also look at the same gender, the following is true:
Select Name,sex,count (*) from A Group by Name,sex have Count (*) > 1

Three
Method One

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

Database Query Duplicate data