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DISTINCT query alternative - retrieve one unique column and the other columns for that row

Posted on 2010-08-19
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Last Modified: 2012-05-10
Hello,

I have a database with a table as follows:

Id - int
poId - int
partNo - varchar(50)
description - text
quantity -int

example data:

1 - 1 - AB100/4 - A screw - 100
2 - 1 - AB100/5 - A bolt - 200
3 - 2 - AB100/4 - A screw - 150

I want to construct a query which will retrieve full rows that have a unique partNo.

So for example I would like to return the following data:

2 - 1 - AB100/5 - A bolt - 200
3 - 2 - AB100/4 - A screw - 150


How can I achieve this? I have tried the following but it doesnt work because it does a DISTINCT on all of the columns selected and therefore displays every row.

SELECT DISTINCT partNo, Id, poId, description, quantity FROM poLineItems
Order By Id DESC


Any ideas?
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Comment
Question by:amgrobins
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15 Comments
 
LVL 18

Expert Comment

by:Cluskitt
ID: 33474823
select partNo, Id, poId, description, quantity FROM poLineItems as p1 inner join (select distinct partNo from poLineItems) as p2 on p1.Id=p2.Id
Order By Id DESC
0
 

Author Comment

by:amgrobins
ID: 33474849
i got the following error:


Msg 207, Level 16, State 1, Line 1
Invalid column name 'Id'.
Msg 209, Level 16, State 1, Line 1
Ambiguous column name 'partNo'.
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Expert Comment

by:Rajkumar Gs
ID: 33474897
Can you elaborate your requirement ?

Raj
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Author Comment

by:amgrobins
ID: 33474907
I want every unique value from ONE column. but i also want the data from the other columns for each unique row.
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Expert Comment

by:Rajkumar Gs
ID: 33474911
In your expected result, the part number 'AB100/4' is contains in other record. ?
What do you mean by unique partno ?

Raj
0
 

Author Comment

by:amgrobins
ID: 33474928
AB100/4 may occur 100 times. In my result set I only want the most recent entry of AB100/4 along with the quantity, description, poId
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Expert Comment

by:Cluskitt
ID: 33474954
select p1.partNo, p1.Id, poId, description, SUM(quantity) FROM poLineItems as p1 inner join (select max(id) as id2, partNo from poLineItems group by partNo) as p2 on p1.Id=p2.Id2
Group by p1.partNo, p1.Id, poId, description
Order By Id DESC
0
 
LVL 18

Expert Comment

by:Cluskitt
ID: 33474962
That will give the sum of all the items you have... if you only want the last value, remove sum, and the group by line in the end.
0
 
LVL 23

Expert Comment

by:Rajkumar Gs
ID: 33474977
Replace tablename with yours
Raj
select * from
(
select *, row_number() over(partition by partNo order by id desc) rowno
from #table
) a
where a.rowno = 1

Open in new window

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Accepted Solution

by:
Rajkumar Gs earned 500 total points
ID: 33475146
Updated my query little bit with necessary columns and sort by id
Raj
select Id, poId, partNo, description, quantity 
from
(
	select *, row_number() over(partition by partNo order by id desc) rowno
	from #table
) a
where a.rowno = 1
order by id

Open in new window

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LVL 32

Expert Comment

by:awking00
ID: 33492575
RajkumarGS' query should work fine as long as you have SQL Server 2005 or later.
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Expert Comment

by:Rajkumar Gs
ID: 33492682
awking is right. If you have SQL Server below v2005, try this query

Raj
select a.* from #table a
inner join
(
select partNo, max(id) as id from #table
	group by partNo
) b on a.id = b.id

Open in new window

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Author Closing Comment

by:amgrobins
ID: 33839689
A+
0
 
LVL 23

Expert Comment

by:Rajkumar Gs
ID: 33840690
Nice to see you got the solution.

Thanks for the points
Raj
0
 

Author Comment

by:amgrobins
ID: 33840695
:)
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