mysql查询问题，求大神

Question

Answer 1

select year, sum(case month when 1 then amount else 0 end) as m1, sum(case month when 2 then amount else 0 end) as m2, sum(case month when 3 then amount else 0 end) as m3, sum(case month when 4 then amount else 0 end) as m4
from table group by year