If data entries already exist...

[Cory_nz]

Hey people

New on here, so be gentle...

I have a table named 'ASSESSMENT' which creates a primary key '_pk_assessment_id'. Within that table there are also two foreign keys, '_fk_student_id' and also '_fk_unit_id' which both link back to the STUDENT and UNIT table respectively.

What I would like to know is, how can I put in a conditional (and what do I need to put) if I want to check if the combination of _fk_student_id & _fk_unit_id exists within another _pk_assessment_id row of data.

Not sure if I've explained it properly, but basically there can every only be one instance of the combination between _fk_student_id & _fk_unit_id and I want to check everything to ensure that happens.

If I haven't explained myself properly then let me know. Anyone have any ideas?

thanks in advance for your help.

[comment]

See if this helps:

http://fmforums.com/forum/showpost.php?post/249317/