SELECT department, ROUND(AVG(normal_salary - dock_salary), 2) AS average_actual_salary, #计算所有员工的平均实际工资 ROUND(COALESCE(AVG(CASE WHEN staff_gender = 'male' THEN normal_salary - dock_salary END), 0), 2) AS average_actual_salary_male, #迭代表筛选出所有staff_gender为male的行,计算出行对应的实际工资,然后对所有行求平均。若为空值则返回0。 ROUND(CO...