On Tue, Jul 25, 2006 at 12:58:55AM +0000, Kayteck wrote: > I have two tables joined by foreign key id_przelewu, and for some rows > results of queries with NATURAL JOIN and JOIN ... USING (...) differs ! I've > readed that NATURAL JOIN is only shorthand for the second method, but this > results shows that's not true: [...] > select id_przelewu,id_zamowienia from zamowienia natural join przelew where > id_klienta=4999; > id_przelewu | id_zamowienia > -------------+--------------- > (0 rows)
Do zamowienia and przelew have column names in common in addition to id_przelewu? NATURAL JOIN uses all common column names, not just those specified in a foreign key constraint. http://www.postgresql.org/docs/8.1/interactive/queries-table-expressions.html#QUERIES-FROM "Finally, NATURAL is a shorthand form of USING: it forms a USING list consisting of exactly those column names that appear in both input tables." http://www.postgresql.org/docs/8.1/interactive/sql-select.html#SQL-FROM "NATURAL is shorthand for a USING list that mentions all columns in the two tables that have the same names." -- Michael Fuhr ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
