Hello Markus, It's actually a temporary mailbox just in case the list attracts spam :-)
Thank you for your help, I will study it when I get development time on the database. On 03/05/06, Markus Schaber <[EMAIL PROTECTED]> wrote:
Hi, Ed Temp, [EMAIL PROTECTED] wrote: > First post, be gentle as I have terminology problems and so the > subject might be wrongly worded. Hmm, the biggest mistake seems that "et temp 01" is a very unlikely real name, so you should reconfigure your mail client :-) > What I am trying to construct is a *single* query showing the total > number of males in the table > and also the total number of male vegetarians in the table, i.e. the > 2nd value is computed on a subset of the records needed for the first > value. > > As 2 queries this would be: > select count(*) from mytab where gender='m' > select count(*) from mytab where gender='m' and diet_pref='veg' Have you tried to UNION ALL the two queries? > The table is big and I'd like to do the select where gender='m' only > once. (In the actual situation the select is on a date range) SELECT count(*),diet_pref='veg' FROM table WHERE gender='m' GROUP BY diet_pref='veg' Is not exactly what you want, as your application still has to add two numbers to get the total result, but avoids the duplicated table scan. SELECT count(*),count(nullif(diet_pref='veg', f)) FROM table WHERE gender='m' Should also give you both counts, this time in different columns, also avoiding the duplicated table scan. It relies on the fact that count(something) is only called if something is not null, whereas count(*) is called for every row (as a special case). HTH, Markus -- Markus Schaber | Logical Tracking&Tracing International AG Dipl. Inf. | Software Development GIS Fight against software patents in EU! www.ffii.org www.nosoftwarepatents.org
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