Stephan Szabo <sszabo@xxxxxxxxxxxxxxxxxxxxx> writes: > On Thu, 23 Mar 2006, Bradley Kieser wrote: >> last_backup: timestamp >> backup_unit: integer - Represents day, week, quarter, annual, etc. The >> text is stored in backup_code (e.g. 'days', 'months') >> backup_period: integer - Represents the skip factor. > CAST( backup_period || ' ' || backup_code AS interval) should give you an > interval. If the units were constant, I'd say that using integer * > interval is a better idea, but I think you'd need a function that say took > backup_unit and gave back an interval of 1 <unit> to make that work, but > that would possibly be cleaner overall. This really seems like a case of a poorly chosen representation. Why not just have the backup interval as an interval column, ie last_backup: timestamptz (not timestamp, btw) backup_interval: interval, can be eg '3 days' or '1 month' or whatever. Then you can do WHERE last_backup + backup_interval <= current_timestamp regards, tom lane
