Quick and dirty solution which would not scale that well but works as below. You may want to investigate

CLR concatenate aggregate[/url]

declare @a table (Linenumber int, ErrorText varchar(30),FileID int)

insert into @a values

(1, 'a', 10),

(1, 'b', 10),

(2, 'a', 11),

(2, 'b', 11),

(2, 'c', 11),

(3, 'c', 12),

(3, 'd', 12)

select * from @a

declare @FileID int, @LineNumber int

declare FileIDCursor cursor for select distinct FileID, LineNumber from @a

declare @AggResult table (LineNumber int, ErrorText varchar(1000), FileID int)

open FileIDCursor

fetch next from FileIDCursor into @FileID, @LineNumber

while @@FETCH_STATUS = 0

begin

declare @Concat varchar(1000) = ''

select @Concat = @Concat + ErrorText + ','

from @a

where FileID = @FileID and linenumber = @LineNumber

insert into @AggResult

select @LineNumber, left(@Concat,len(@Concat)-1), @FileID

fetch next from FileIDCursor into @FileID, @LineNumber

end

close FileIDCursor

deallocate FileIDCursor

select * from @AggResult

Fitz