Compare the average pay rate of male and female employees.
male refers to Gender = 'M'; female refers to Gender = 'F'; difference in average rate = DIVIDE(AVG(Rate where Gender = 'F')), (AVG(Rate where Gender = 'M'))) as diff;
SELECT AVG(T2.Rate) FROM Employee AS T1 INNER JOIN EmployeePayHistory AS T2 ON T1.BusinessEntityID = T2.BusinessEntityID GROUP BY T1.Gender