Query to display null fields.

[dazibit]

I have a query where I am calculating the average amount of hours a student does homework.

The database contains students in secondary and post secondary.

Is there a way to display a value of N/A or 0 for the average of students which it doesn't apply to and have 0 or null in both fields of secondary and post secondary?

[rpeare]

HomeworkHoursModified: nz([homework_hours], 0)

if you were going to display it it in a query