求大神帮忙写个SQL语句啊 急用 谢谢

表名叫T_MH_TARGET_SUM 根据year，month，把month为11的sum_ndmb的值赋给相同sum_object_id，month为12的
[解决办法]

meger into T_MH_TARGET_SUM t2 using(select * from T_MH_TARGET_SUM  where t.month=11) t1 on (t1.sum_object_id=t2.sum_object_id and t2.month=12)
when matched then
update t2 set t2.sum_ndmb=t1.sum_ndmb;