sql - Microsoft Access: Basing one combo box on another from the same row

Question

I have 2 tables:

Table1 tblStaff contains 2 fields:

1. StaffID (Numbers)
2. StaffName (Text)

Table2 tblTraining contains 3 fields:

1. TrainingID (Numbers)
2. Trainee (Combo Box)
3. Passed (Combo Box)

I would like the available options in [Passed] be those selected in [Trainee]. Say there are 4 staff Tony, Amy, Bay and Linda on tblStaff. If Tony, Bay and Linda are selected in [Trainee] then [Passed] on the same row will only display Tony, Bay and Linda for selection. Say on another row Amy and Bay have been selected in [Trainee], Amy and Bay shall be the only options available for [Passed] on the same row.

So basically I want [Passed] of different row of the same table to display different options subject to the user selection on Trainee. I wonder if this can be achieved by purely sql. I don't wanna get into VBA. Thanks.