SQL Not A Single Group Group Function

Question

Okay guys here is the question. I have to list the department ID, department name, count of sales reps, and average commission rate for each department. Also I need to Group by

Answer 1

rewrite this way and see if it gives you what you want...

SELECT d.Dept_ID, d.Dept_Name, 
  Count(r.Sales_Rep_ID) NumOfSalesR, 
  c.Comm_Rate AVGCOM 
FROM DEPT_arb d, 
   Join SALES_REP_arb r
       On r.Dept_ID = d.Dept_ID 
   Join COMMISSION_arb c
       On c.Comm_Class = r.Comm_Class
Group By d.Dept_ID, d.Dept_Name, c.Comm_Rate 
Where c.Comm_Rate = 
       (Select AVG(Comm_Rate)
        From COMMISSION_arb 
        Where Comm_Class = r.Comm_Class)
Order By c.Comm_Rate;