简单的mySQL小组问题

Question

如果在mysql表中保留有DATE_ARRIVAL，DATE_DEPARTED和TOTAL_EARN列

我如何Group By月，2010中的所有收入？

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);

虽然这取决于您希望以谓词为基础的列（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