Hi all,  I am pretty new with MS access and I am trying to get a field
in a table to be automatically calculated when another field is
updated.

I have designed a form, and this works happily.  I use
=[yield_test_1]/[yield_test_2] in the form.  However, this doesn't
update the table that the form was created from.

Putting that in the table doesn't work either.

Is there a way of doing this without running a query? 

Thanks,

JM

P.S.  If the answer's more complicated than I suspect, I'll tip (check
out my other questions for evidence of this), faster answers also get
a tip.