SQL not a single group group function error

Question

I am having a hard time getting my oracle developer query to output correctly. When I have the avg function in it, it gives me not a single group group error. When I take it

Answer 1

For your newly added fields, you didn't used group by, hence you are getting this error, so by including that newly added fields to group by you will resolve this error and group all the data that would have to be aggregated.