Re: NEWBIE: How do I get the oldest date contained in 3 tables - Mailing list pgsql-general

"Dann Corbit" <DCorbit@connx.com> writes:
>> owner@postgresql.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