theAverage is a table. In order to reference another table in an update statement you need to specify that table as part of the from and list the columns that are going to match up. The select statement isn't needed.
Code:
update Table
set Field = Avg(theAverage.Field1+theAverage.Field2)
from theAverage
where ...
group by Avg(theAverage.Field1+theAverage.Field2)
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.