经典sql总结(2)

如何做呢，跟上文区别不大。

我建个表，输入以下

 select year,
 (select amount from info2 as t2 where t2.year=t.year and t2.mouth=1) as m1,
 (select amount from info2 as t3 where t3.year=t.year and t3.mouth=2) as m2,
 (select amount from info2 as t4 where t4.year=t.year and t4.mouth=3) as m3
 from info2 as t group by year;