Re: join question

On Fri, 18 Oct 2002, Frank Morton wrote:

> For the SQL gurus, a query where I'm not getting the expected
> results. Trying to write it using sql compatible with both postgres
> and mysql.
>
> There are two tables:
>
> table = profile
> int id
> char name
>
> table = attribute
> int id
> int containerId
> char name
> char value
>
> Multiple attribute rows correspond to a single profile row where
> attribute.containerId = profile.id
>
> These two queries result in one row being returned, which is
> the expected result:
>
> select name from profile where ((profile.state='1020811'));
>
> select profile.name from profile,attribute where
> (((attribute.name='description') and (attribute.value='1020704') and
> (profile.id=attribute.containerId)));
>
> But, I thought this next query would just be a simple way to combine the two
> queries with an "or" operator, still returning one row, actually returns
> ALL rows of attribute:
>
> select profile.name from profile,attribute where
> ((profile.state='1020811') or ((attribute.name='marketsegment') and
> (attribute.value='1020704') and (profile.id=attribute.containerId)));
>
> Why doesn't this last query return just one row?

Because for each combination of rows from profile and attribute where
profile.state='1020811' the where clause is statisfied.

I'm not sure what you're precisely trying to get out, since unless the
row that matches each of the clauses is the same I don't see how you'd
only get one row out with an or.