Specify the following additional queries on the database of Figure 3.5 in SQL. Show the query results if applied to the database of Figure 3.6.
(a) For each department whose average employee salary is more than $30,000, retrieve the department name and the number of employees working for that department.
(b) Suppose we want the number of male employees in each department rather than all employees (as in Exercise 5.4a). Can we specify this query in SQL? Why or why not?