Re: SQL challenge--top 10 for each key value?
От | Rod Taylor |
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Тема | Re: SQL challenge--top 10 for each key value? |
Дата | |
Msg-id | 1081560594.56361.818.camel@jester обсуждение исходный текст |
Ответ на | Re: SQL challenge--top 10 for each key value? (Greg Stark <gsstark@mit.edu>) |
Ответы |
Re: SQL challenge--top 10 for each key value?
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Список | pgsql-sql |
On Fri, 2004-04-09 at 18:43, Greg Stark wrote: > Josh Berkus <josh@agliodbs.com> writes: > > > Rod, > > > > > Something along the lines of the below would accomplish what you want > > > according to spec. ROW_NUMBER() is a spec defined function. (6.10 of > > > SQL200N) > > > > Great leaping little gods! They added something called "row number" to the > > spec? > > > > Boy howdy, folks were right ... the ANSI committee really has completly blown > > off the relational model completely. > > If it's like Oracle's rownum then it's the row number of the *output*, not the > position on disk. So it's not entirely blowing off the relational model any > more than ORDER BY does. > > The weird thing is the number of cases where you want ORDER BY or rownum > inside subselects. Which the solution to the original question needed. It's not really like Oracles row num at all, though I suppose you can emulate rownum using it. The intention is that you will use it for "aggregates" like running totals, moving averages, counting, etc. http://www.devx.com/getHelpOn/10MinuteSolution/16573/1954?pf=true
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