Re: Different type of query

On Wed, 2008-06-11 at 14:41 -0400, PostgreSQL Admin wrote:
> I would like to have multiple values nutrient_no:
> ndb_no | nutrient_no | nutrient_value
> --------+-------------+----------------
>  13473 |         203 |          24.18
>  13473 |         204 |          15.93
>  13473 |         205 |              0
>  13473 |         207 |            1.1
>  13473 |         208 |            247
>  13473 |         221 |              0
> 
> I'm thinking:
> select nutrient_no, nutrient_value from nutrient_data where ndb_no = 
> 13473 and (nutrient_no = '203' or nutrient_no = '204' or nutrient_no =
> 208);
> 
> 
> Now is that the most efficient SQL query?
> 
> Thanks,
> J

It seems that you'd want to do something like:

select nutrient_no, nutrient_value from nutrient_data where ndb_no =
13473 and nutrient_no in (203, 204, 208..)

You could also grab the most significant 8 nutrients by doing something
like:

select nutrient_no, nutrient_value from nutrient_data where ndb_no =
13473 order by nutrient_value desc limit 8

-Mark