Alert on duplicate field

[Chillax'n]

Can somebody please help.



I would like to build in an alert that appears on the screen when duplicate information is entered into a field. I would like the alert to appear if there are 5 repetitions over a 4 week period, ie if somebody's name comes up 5 times in 4 weeks the user is alerted.

Any assistance would be greatly appreciated.

[orange]

Why not just prevent duplicates? What's with allowing x repetitions over some time frame???

[Chillax'n]

I expect the field to have duplicates, this is fine.
For example, if people borrow equipment, I want to restrict the borrowing of different equipment to 5 pieces over a 4 week period.
If recording incidences, you are able to have 5 incidences over a 4 week period.

[orange]

Interesting example, but I don't see where this would fit in a business type rule. It's certainly a valid "sample" to program.

Check today's date;go back to a date 4 weeks ago;
collect all borrowings by people and count the number of borrowings in this time period by person, identify where the count >5. if you really want to check for different equipment in each borrowing, then that's the next step.