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Unique records

Posted on 2009-05-06
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Last Modified: 2012-05-06
I have a table that has the following sample information:

ID_NUM                                                   VER               PN
-------------------------------------               ----                ------------------
0000000000000000001000016      001      2T-MNILA-AA
0000000000000000001000019      001      338602-121
0000000000000000001000019      001      338602-161
0000000000000000001000019      001      338602-291
0000000000000000001000019      001      338602-A21
0000000000000000001000019      001      338602-AA1
0000000000000000001000019      001      338602-AB1
0000000000000000001000019      001      338602-001
0000000000000000001000019      001      338602-371
0000000000000000001000019      001      338602-391
0000000000000000001000019      001      338602-AD1
0000000000000000001000020      001      36-60382-25
0000000000000000001000023      001      DY-1280A-AD
0000000000000000001000024      001      DS-SWRCA-AA
0000000000000000001000025      001      CT-WNTER-20
0000000000000000001000031      001      36-60382-25
0000000000000000001000032      001      CT-NOVUS-BC
0000000000000000001000032      001      CT-NOVUS-CC
0000000000000000001000032      001      CT-NOVUS-DC
0000000000000000001000033      001      3X-75CAA-AA
0000000000000000001000034      001      70-40530-03
0000000000000000001000035      001      263661-002
0000000000000000001000035      001      339100-001

I need to create a function or sql statement that can identify the first record when there are multiple records in the table.  If I use the group-by function, it doesn't find the unique ones.
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Question by:Fairfield
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Expert Comment

by:chapmandew
ID: 24318767
well, I don't know how you designate "first", but here is a way to do it:

select * from (
select *, ranking = dense_rank() over(partition by id_num order, ver order by pn, newid())
from tablename
) a
where ranking = 1
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Expert Comment

by:momi_sabag
ID: 24318772
do you mean

with a as (Select *, row_number() over(partition by id_num order by ver) as row
from your_table)

select * from a where rown=1
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Accepted Solution

by:
BrandonGalderisi earned 2000 total points
ID: 24318777
What won't this show you?

select id_num,ver,min(pn)
from SomeTable
group by id_num,ver
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LVL 60

Expert Comment

by:chapmandew
ID: 24318884
hmmm....while Brandons solution does work, so do the others....
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Expert Comment

by:BrandonGalderisi
ID: 24318930
While they will all function.  I personally chose my method due the fact that row_number() would not have to assign a value to every record then filter.
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Expert Comment

by:chapmandew
ID: 24318960
true...but its almost exactly the same way min() works.
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