第五题sql怎么写啊我写的select case when year(birth)>=1990 and year(birth) when year(birth)>=2000 and year(birth) end as 年龄段, sum(余额字段)(忘了) as '余额' from xxx,xxxwhere xxx xxx group by 年龄段测试通过了,但是提交它显示0% #恒生笔试#