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Re: Different type of query

From: PostgreSQL Admin <postgres(at)productivitymedia(dot)com>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: Different type of query
Date: 2008-06-11 19:00:28
Message-ID: 485020CC.3030805@productivitymedia.com (view raw or flat)
Thread:
Lists: pgsql-sql
Mark Roberts wrote:
> 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
>
>
>   
Thanks Mark!

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