Saturday, September 20, 2008

[GENERAL] Getting several columns from subselect with LIMIT 1

I have a PERSONS table.
I also have a PROGENY table, which is a many-to-many association table
with two foreign keys to the PERSONS table to itself.
(In this day and age, not only can an individual have any number of
children, but also a person can have any number of parents! At least,
let's assume that's true for the sake of this setup.)

Suppose I wish to construct a view of the persons, along with the name
of their first-born (if they have one; NULL otherwise). The
following SELECT does just that:

FROM progeny JOIN persons child ON = progeny.child
WHERE progeny.parent =
ORDER BY child.birthdate ASC
) AS firstborn_name
FROM persons;

Now, this is probably not the most elegant piece of code, but the real
problem is that
I cannot see how to extend it to the case where I want not only the
firstborn's name but also the firstborn's ID
(short of repeating the entire subselect a second time). At the
moment, with this current syntax, my subSELECT statement would not be
allowed to return more than a single column.

Any suggestion?

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