I know this has been discussed in the past, but no amount of keywords has returned anything from the archives.
I want to create a courtesy car diary diary system where I have a table containing all of the cortesy cars in the pool, and then an allocation table which has two timestamps, one for the start date/time and one for the return date/time.
How do I go about creating constraints on inserts and updates to ensure that
a) the finish is after the start
check constraint like -> "finish_time > start_time" this will do
b) two allocations for a single vehicle don't overlap.
Use "overlaps" function in a trigger to validate the above.
-- Gary Stainburn
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