createviewtot_credits(year,num_credits)as(selectyear,sum(credits)fromsectionnaturaljoincoursegroupbyyear);报错消息156，级别15，状态1，过程tot_credits，第4行关键字'group'附... create view tot_credits(year,num_credits) as
(select year , sum(credits)
from section natural join course
group by year);
报错

消息 156，级别 15，状态 1，过程 tot_credits，第 4 行
关键字 'group' 附近有语法错误。
求解决~