Re: RE: Re(2): optimize sql
От | pgsql-sql@fc.emc.com.ph (pgsql-sql) |
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Тема | Re: RE: Re(2): optimize sql |
Дата | |
Msg-id | fc.000f5672005a3569000f5672005a3569.5a35b7@fc.emc.com.ph обсуждение исходный текст |
Ответ на | Re(2): optimize sql (pgsql-sql@fc.emc.com.ph (pgsql-sql)) |
Список | pgsql-sql |
but active is a boolean field. HLafleur@phoenixforge.com writes: >If you know that 't' will always be the highest character in the active >field for all records: > >SELECT name FROM office, office_application >WHERE code = office_code >GROUP BY name >HAVING MAX(active) < 't' > >Of course, if you have an active that is 'z' for example, then this won't >work. I think this should work also regardless of max(active) for the >table: > >SELECT name FROM office, office_application >WHERE code = office_code AND active <= 't' >GROUP BY name >HAVING MAX(active) < 't' >UNION >SELECT name FROM office, office_application >WHERE code = office_code AND active >= 't' >GROUP BY name >HAVING MIN(active) > 't' > >Henry > > >-----Original Message----- >From: pgsql-sql@fc.emc.com.ph [mailto:pgsql-sql@fc.emc.com.ph] >Sent: Wednesday, July 26, 2000 9:40 PM >To: pgsql-sql@postgresql.org; reedstrm@rice.edu >Subject: Re(2): [SQL] optimize sql > > >reedstrm@rice.edu writes: >>How does the output of the above differ from: >> >>SELECT name FROM office, office_application >>WHERE code = office_code >>AND active != 't'; >> >>Without knowing the table structures (which tables to active, code, >>and office_code belong to?) it's hard to suggest much else. >> >>Ross > > >The name and code fields belong to office table. While >office_code and active fields belong to office_application table. >The name field have duplicates and among the duplicates, >only one active field is TRUE. I just wanted to get name field >that has no TRUE active field. Any other idea? Thanks. > >sherwin
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