mysql-group group by month

select sum(grosspay),datestart,year(datestart)*12+month(datestart) from payroll group by year(datestart)*12+month(datestart);



select sum(grosspay),datestart,year(datestart)*12+month(datestart)
from payroll
where year(datestart)*12+month(datestart)>24163
group by year(datestart)*12+month(datestart);