Checking ranges across multiple records
I'm relatively new to FMPro and am stuck on a specific task! I'm writing a simple equipment bookings database which has two core tables - one for the items being booked and a related table for the bookings themselves. When a person makes a booking for a particular item I'd like to write a script that checks whether the current booking dates (from and to) overlap with existing bookings - so I need to check across all existing booking records for the item being booked and see whether their date_from and date_to fields fall within the range currently being booked.
Any ideas how I do this?