Remove duplicate row based on select statement - sql

Question

I have two select statements which is returning duplicated data. What I'm trying to accomplish is to remove a duplicated leg. But I'm having hard times to get to the second row programmatically.
select i.InvID, i.UID, i.StartDate, i.EndDate, i.Minutes,i.ABID from inv_v i, InvoiceLines_v i2 where
i.Period = '2014/08'
and i.EndDate = i2.EndDate
and i.Minutes = i2.Minutes
and i.Uid <> i2.Uid
and i.abid = i2.abid
order by i.EndDate
This select statement returns the following data.
As you can see it returns duplicate rows where minutes are the same ABID is the same but InvID are different. What I need to do is to remove one of the InvID where the criteria matches. Doesn't matter which one.
The second select statement is returning different data.
select i.InvID, i.UID, i.StartDate, i.EndDate, i.Minutes from InvoiceLines_v i, InvoiceLines_v i2 where
i.Period = '2014/08'
and i.EndDate = i2.EndDate
and i.Uid = i2.Uid
and i.Abid <> i2.Abid
and i.Language <> i2.Language
order by i.startdate desc
In this select statement I want to remove an InvID where UID is the same then select the lowest Mintues. In This case, I would remove the following InvIDs: 2537676 , 2537210
My goal is to remove those rows...
I could accomplish this using cursor grab the InvID and remove it by simple delete statement, but I'm trying to stay away from cursors.
Any suggestions on how I can accomplish this?

Answer 1

You can use exists to delete all duplicates except the one with the highest InvID by deleting those rows where another row exists with the same values but with a higher InvID
delete from inv_v
where exists (
select 1 from inv_v i2
where i2.InvID > inv_v.InvID
and i2.minutes = inv_v.minutes
and i2.EndDate = inv_v.EndDate
and i2.abid = inv_v.abid
and i2.uid <> inv_v.uid -- not sure why <> is used here, copied from question
)

Answer 2

I have faced similar problems regarding duplicate data and some one told me to use partition by and other methods but those were causing performance issues
However , I had a primary key in my table through which I was able to select one row from the duplicate data and then delete it.
For example in the first select statement "minutes" and "ABID" are the criteria to consider duplicacy in data.But "Invid" can be used to distinguish between the duplicate rows.
So you can use below query to remove duplicacy.
delete from inv_i where inv_id in (select max(inv_id) from inv_i group by minutes,abid having count(*) > 1 );
This simple concept was helpful to me. It can be helpful in your case if "Inv_id" is unique.

Answer 3

;WITH CTE AS
(
SELECT InvID
,[UID]
,StartDate
,EndDate
,[Minutes]
,ROW_NUMBER() OVER (PARTITION BY InvID, [UID] ORDER BY [Minutes] ASC) rn
FROM InvoiceLines_v
)
SELECT *
FROM CTE
WHERE rn = 1

Answer 4

Replace the ORIGINAL_TABLE with your table name.
QUERY 1:
WITH DUP_TABLE AS
(
SELECT ROW_NUMBER()
OVER (PARTITION BY minutes, ABID ORDER BY minutes, ABID) As ROW_NO
FROM <ORIGINAL_TABLE>
)
DELETE FROM DUP_TABLE WHERE ROW_NO > 1;
QUERY 2:
WITH DUP_TABLE AS
(
SELECT ROW_NUMBER()
OVER (PARTITION BY UID ORDER BY minutes) As ROW_NO
FROM <ORIGINAL_TABLE>
)
DELETE FROM DUP_TABLE WHERE ROW_NO > 1;