On Mon, Apr 19, 2010 at 12:47 PM, Vladimir Rybas <[email protected]> wrote: > They're not the same, right. > I mean, it depends on what you need. The real ID or just an amount of > records. > But If task is to get random record you will > Company.all[rand(Company.count)] but not > Company.all[rand(Company.last.id)]
I assume you meant find rather than all. Neither of these will work in the face of deleted records, picking a random record is a bit tricky. One way, which might not work for all databases, but assuming a mysql database might be: Company.first( :order => "Rand()") But this isn't very efficient and might not work for tables with lots of records. Another approach is something like. Company.first(:conditions => ["id <= ?", rand(Company.last.id) + 1] This should always return a random record (unless the table is empty), but the records won't be evenly distributed because the probability of selecting a particular record is proportional to the difference between it's id and the id of the preceding existing record if any, or 0. -- Rick DeNatale Blog: http://talklikeaduck.denhaven2.com/ Github: http://github.com/rubyredrick Twitter: @RickDeNatale WWR: http://www.workingwithrails.com/person/9021-rick-denatale LinkedIn: http://www.linkedin.com/in/rickdenatale -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
