Re: [GENERAL] Check for an empty result
Hi Craig! --- On Fri, 2/13/09, Craig Ringer cr...@postnewspapers.com.au wrote: Eus wrote: Hi Ho! Is there a way to check whether or not a subquery returns an empty result set? EXISTS SELECT blah FROM blah WHERE EXISTS (SELECT 1 FROM tablename WHERE ...); Thank you. Previously I tried: ... WHERE (...) IS NULL;. Of course, it didn't work. postgre check empty result set It's not postgre. It's PostgreSQL, or postgres. This matters when you're searching. Oh, okay. Thanks for telling me. -- Craig Ringer Best regards, Eus (FSF member #4445) In this digital era, where computing technology is pervasive, your freedom depends on the software controlling those computing devices. Join free software movement today! It is free as in freedom, not as in free beer! Join: http://www.fsf.org/jf?referrer=4445 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Check for an empty result
Hi Andreas! --- On Fri, 2/13/09, A. Kretschmer andreas.kretsch...@schollglas.com wrote: In response to Eus : Hi Ho! Is there a way to check whether or not a subquery returns an empty result set? You can use EXISTS for that: -- empty result test=*# select * from (select 1 where 1=2) foo; ?column? -- (0 rows) That's good that it can be used in FROM phrase too besides WHERE phrase. -- check if a result exists test=*# select exists(select * from (select 1 where 1=2) foo); ?column? -- f (1 row) test=*# select exists(select * from (select 1 where 1=1) foo); ?column? -- t (1 row) Even in SELECT phrase? That's great! Thank you for the information. Regards, Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: - Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net Best regards, Eus (FSF member #4445) In this digital era, where computing technology is pervasive, your freedom depends on the software controlling those computing devices. Join free software movement today! It is free as in freedom, not as in free beer! Join: http://www.fsf.org/jf?referrer=4445 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
[GENERAL] Check for an empty result
Hi Ho! Is there a way to check whether or not a subquery returns an empty result set? Googling with the following keywords does not help: postgre check empty result set sql check empty result Thank you. Best regards, Eus (FSF member #4445) In this digital era, where computing technology is pervasive, your freedom depends on the software controlling those computing devices. Join free software movement today! It is free as in freedom, not as in free beer! Join: http://www.fsf.org/jf?referrer=4445 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Check for an empty result
Eus wrote: Hi Ho! Is there a way to check whether or not a subquery returns an empty result set? EXISTS SELECT blah FROM blah WHERE EXISTS (SELECT 1 FROM tablename WHERE ...); postgre check empty result set It's not postgre. It's PostgreSQL, or postgres. This matters when you're searching. -- Craig Ringer -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Check for an empty result
In response to Eus : Hi Ho! Is there a way to check whether or not a subquery returns an empty result set? You can use EXISTS for that: -- empty result test=*# select * from (select 1 where 1=2) foo; ?column? -- (0 rows) -- check if a result exists test=*# select exists(select * from (select 1 where 1=2) foo); ?column? -- f (1 row) test=*# select exists(select * from (select 1 where 1=1) foo); ?column? -- t (1 row) Regards, Andreas -- Andreas Kretschmer Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: - Header) GnuPG-ID: 0x3FFF606C, privat 0x7F4584DA http://wwwkeys.de.pgp.net -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
