True, and so the plot thickens...
On Feb 25, 8:20 pm, Anthony <abasta...@gmail.com> wrote: > 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
