Validate two fields to avoid duplicate records

[Novine]

Aloha All

I am trying to create a validation so that duplicate records are not entered.

I have a lunch order database. Each child can order once per month. I want to create a validation that when a second record is entered for a student in the same month a message warns the data entry person.

Any suggestions

Thanks in advance

[Pupiweb]

Create a calc field Month = Month(OrderDate)

Create a calc field Year = Year(OrderDate)

Create a calc field Combo = ChildID & " " & Month & " " & Year

Create a self join relationship Combo::Combo

Add this validation in field OrderDate and ChildID

If (Count (Self join::ChildID)>0);0;1)

(Note:I don't like how FM handles failed validations)