finding records with no related ones in a child table
I have a student table and an appointment table and need to browse students with no future appointments. So this is what I did:
I created a global field in the student table and assigned to it the current date. Then I related the appointment table to the student table with the following relation
student::code = Appointment:: code ( code is the student code)
student::datefilter < appointment::date (datefilter is the global field in student table and has the value of current date)
Now when I try to perform a find to browse students with future booking I have no problem but when I try to find the ones without I tried:
or Appointment::date ?
or appointment::date < today
None of the above is working, what am I doing wrong?