Re: [HACKERS] correlated subquery

> 
> >Is this a good example of a required correlated subquery:
> >
> >    SELECT f1.firstname, f1.lastname, f1.age
> >    FROM friends f1
> >    WHERE age = (
> >                 SELECT MAX(age)
> >                 FROM friends f2
> >                 WHERE f1.state = f2.state
> >                )
> >    ORDER BY firstname, lastname
> >
> >It finds the oldest person in each state.  HAVING can't do that, right?
> 
> I'm assuming that this is for the book... If so, you might want to also
> note that this query can return more people than there are states if
> multiple people in the same state have the maximum age for that state.
> 
> I'm not sure how deeply you are going into this, but getting only one
> person per state looks like it might be fairly painful... You might be
> able cheat if there was only one field besides age and state in the output
> using group by and an aggregate.

Yikes, that would be painful.  Good point.  Fortunately, the data has
only one max person per state.

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