On Friday, February 25, 2011 4:25:00 PM UTC-5, DenesL wrote: > > > The problem is checking against all dates already in the DB. > To avoid that I would have another table with the max(to_dates) and > min(from_dates) of all DB values, those will be updated with each new > insert if required. > > Why those values? to avoid any overlaps, then your new values must be > such that > to_date < min(from_dates) and from_date > max(to_dates)
Doesn't this just ensure that the new range is entirely before the earliest or after the latest existing range? What if you want to insert a range that fills a gap within the existing set of ranges -- wouldn't you have to compare against all the existing records in that case? Anthony
