Union and order by
- by David Lively
Consider a table like
tbl_ranks
--------------------------------
family_id | item_id | view_count
--------------------------------
1 10 101
1 11 112
1 13 109
2 21 101
2 22 112
2 23 109
3 30 101
3 31 112
3 33 109
4 40 101
4 51 112
4 63 109
5 80 101
5 81 112
5 88 109
I need to generate a result set with the top two(2) rows for a subset of family ids (say, 1,2,3 and 4) ordered by view count.
I'd like to do something like
select top 2 * from tbl_ranks where family_id = 1 order by view_count
union all
select top 2 * from tbl_ranks where family_id = 2 order by view_count
union all
select top 2 * from tbl_ranks where family_id = 3 order by view_count
union all
select top 2 * from tbl_ranks where family_id = 4 order by view_count
but, of course, order by isn't valid in a union all context in this manner. Any suggestions? I know I could run a set of 4 queries, store the results into a temp table and select the contents of that temp as the final result, but I'd rather avoid using a temp table if possible.
Note: in the real app, the number of records per family id is indeterminate, and the view_counts are also not fixed as they appear in the above example.
