SQL Delete duplicate data keep only one

With SQL statements, delete duplicates and keep only one

In thousands of records, there are some of the same records, how can you use SQL statements to delete duplicates?

1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to judge

SELECT * from People

where Peopleid in (select Peopleid from People 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

Delete from people

where Peoplename in (select Peoplename from People GROUP by Peoplename has count (peoplename) > 1)

and Peopleid not in (select min (peopleid) from people GROUP by Peoplename have Count (peoplename) >1)

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

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

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

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)

6. Remove the first digit to the left of a field:

Update tablename Set [Title]=right [title], (Len ([title]-1)) where Title like ' Village% '

7. Remove the first digit to the right of a field:

Update tablename Set [Title]=left [title], (Len ([title]-1)) where Title like '% Village '

8. Delete Redundant records (multiple fields) in a table without ROWID minimum records

Update vitae set Ispass=-1

where Peopleid in (select Peopleid to Vitae GROUP by Peopleid