易MySQL的集團通過問題

Question

如果在一個MySQL表預訂有DATE_ARRIVAL，DATE_DEPARTED和TOTAL_EARN列

我怎麼Group By個月，都在2010收益？

Answer 1

select monthname(DATE_ARRIVAL),sum(TOTAL_EARN) from RESERVATIONS where DATE_ARRIVAL between '2010-01-01' and '2010-12-31 23:59:59' group by monthname(DATE_ARRIVAL); 

雖然它種取決於你希望你的基礎謂詞的列（DATE_ARRIVAL或DATE_DEPARTED？）

Answer 2

select year(DATE_ARRIVAL) year, month(DATE_ARRIVAL) month, sum(TOTAL_EARN) 
from RESERVATIONS 
group by year, month 
order by year, month