Re: randomized order in select?
От | scott.marlowe |
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Тема | Re: randomized order in select? |
Дата | |
Msg-id | Pine.LNX.4.33.0403110924161.11329-100000@css120.ihs.com обсуждение исходный текст |
Ответ на | Re: randomized order in select? ("Iain" <iain@mst.co.jp>) |
Список | pgsql-sql |
On Thu, 11 Mar 2004, Iain wrote: > If you have a lot of tips, you could create a unique indexed tip number > column. Select the highest tip number using: > > select tip_number from tips order by tip_number desc limit 1; > > Then generate a random number and select using that tip_number. > > Of course, you would have to allow for the possibility of missing tip > numbers, by repeating the random number generation/read sequence until you > find something. Since the tip_number isn't the PK of the table, you can > regenerate the tip numbers to eliminate holes from deletions any time you > like. Just reset the sequence to 1 and update all rows with the > nextval(tipnumber_seq). > > Sounds like a lot of work to me though... Assuming there are ten rows, you can use this: select * from table limit 1 offset random()*10;
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