关于sql日期格式转换

--查查那些数据不符合日期格式

select left(no,4)+'-'+substring(no,5,2)+'-'+right(no,2) from rav
       where isdate(left(no,4)+'-'+substring(no,5,2)+'-'+right(no,2))=0


select cast(left(no,4)+'-'+substring(no,5,2)+'-'+substring(no,7,2) as datetime) from rav