On 4/9/07, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
"Dann Corbit" <DCorbit@xxxxxxxxx> writes: >> owner@xxxxxxxxxxxxxx] 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?
they are all unnecessary :D select least ( (SELECT min(datecol1) FROM table1), (SELECT min(datecol2) FROM table2), (SELECT min(datecol3) FROM table3) ); merlin
