Convert multiple rows in a table into one row based on the primary key

Question

I have 2 tables
CREATE TABLE Files (FileID int, fileName varchar(20))
insert into Files values (1,'F1')
insert into Files values (2,'F2')
insert into Files values (3,'F3')
CREATE TABLE Versions (FileID int, VersionNum varchar(10))
insert into Versions values (1, 'V1')
insert into Versions values (1, 'V2')
insert into Versions values (1, 'V3')
insert into Versions values (2, 'V1')
The two tables join using FileID.  I want a listing of the fileName and the all corresponding versions on one line.  There may not be a version for a file or there may be multiple versions for the file.  The output I want is
F1, V1, v2, v3
F2, V1
F3
Any help would be appreciated.
lg

Answer 1

gardner,
If you want them as different columns, you can PIVOT. However, this requires to know the max numebr of versions that may be there (here I have done with 3). If you dont have that info, then you might have to resort to dynamic SQL..
;with cte
as
select f.fileid,f.fileName,ISNULL(v.VersionNum,'') as VersionNum,row_number() over(partition by f.fileid order by f.filename,v.versionnum) rownum from #files f
left join #versions v
on f.fileid=v.fileid
select fileid,fileName,ISNULL([1],'') as [1],ISNULL([2],'') as [2],ISNULL([3],'') as [3]
from
select * from cte
) tab
PIVOT
Max(VersionNum) for rownum in ([1],[2],[3])
) pvt
Thanks,
Jay
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