with t1 as ( select department,sa.staff_id,staff_gender, (normal_salary - dock_salary) actual_salary from staff_tb st join salary_tb sa using(staff_id) ) select department,round(avg(actual_salary),2) average_actual_salary, ifnull(round(avg(if(staff_gender = 'male',actual_salary,null)),2),0.00) avera...