Yes, a big difference. The first returns the distinct COUNT values, but there is only one, of course. The second returns the number of distinct values in the column.
--------------------------------------------------------------------------- Wei Weng wrote: > This is what is on postgresql's manual page: > > http://www.postgresql.org/idocs/index.php?sql-select.html > > SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] > * | expression [ AS output_name ] [, ...] > [ FROM from_item [, ...] ] > [ WHERE condition ] > [ GROUP BY expression [, ...] ] > [ HAVING condition [, ...] ] > [ { UNION | INTERSECT | EXCEPT } [ ALL ] select ] > [ ORDER BY expression [ ASC | DESC | USING operator ] [, ...] ] > [ FOR UPDATE [ OF tablename [, ...] ] ] > [ LIMIT { count | ALL } ] > [ OFFSET start ] > > According to this syntax, SELECT DISTINCT COUNT(ID) FROM test > should be valid while SELECT COUNT(DISTINCT ID) FROM test otherwise. > > while in fact, both are valid. > > Is there any difference between this two queries? > > Thanks! > > > -- > Wei Weng > Network Software Engineer > KenCast Inc. > > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Don't 'kill -9' the postmaster > -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 359-1001 + If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania 19073 ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/users-lounge/docs/faq.html
