Oracle Lookup Duplicate Record ____oracle

Oracle Lookup Duplicate Records

SELECT *
From T_info A
WHERE (SELECT COUNT (*)
From T_info
WHERE Title = a.title) > 1)
ORDER BY Title DESC

One. Find Duplicate Records

1. Find all duplicate records

SELECT * FROM table Where repeat field in (Select repeating field from table Group by repeating field having Count (*) >1)

2. Filter duplicate records (show only one)

SELECT * from Hzt Where ID in (select Max (ID) from Hzt Group by Title)

Note: A record with the largest ID is shown here

Two. Delete duplicate records

1. Delete all duplicate records (use caution)

Delete table Where Repeat field in (Select repeating field from table Group by repeating field having Count (*) >1)

2. Keep One (this should be the ^_^ that most people need)

Delete hzt Where ID. (Select Max (ID) from Hzt Group by Title)

Note: A record with the largest ID is reserved here

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 Peopleid in (select Peopleid from People GROUP by Peopleid has count (Peopleid) > 1)

and rowID not in (select min (rowid) from people GROUP by Peopleid have Count (Peopleid) >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)

Add:

There are more than two duplicate records, 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 repetition, easier to solve, the use of

SELECT DISTINCT * FROM tablename

You can get a result set without duplicate records.

If the table needs to delete duplicate records (1 of duplicate records are retained), you can delete them in the following ways

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

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)