"Dann Corbit" <DCorbit(at)connx(dot)com> writes:
>> owner(at)postgresql(dot)org] On Behalf Of Lorenzo Thurman
>> I have three tables using date fields. I want to retrieve the oldest
>> date contained in the tables. Can someone show me an example of a query
>> that would do that?
> Just do a union and return the min
That's probably not enough detail for a newbie ...
SELECT min(x) FROM
(
SELECT min(datecol1) AS x FROM table1
UNION ALL
SELECT min(datecol2) AS x FROM table2
UNION ALL
SELECT min(datecol3) AS x FROM table3
) ss;
Exercise for newbie: which of the AS clauses are redundant?
regards, tom lane