求sql语句。关于时间问题

Question

select * from 表 where datediff(week,cast(iyear as char(4))+right(100+imonth,2)+right(100+iday,2),getdate())=0

Answer 1

select * from 表 where datediff(week,convent(datetime(8), imonth+'-'+iday+'-'+iyear,110)=0为什么会出错？

Answer 2

select * from 表 where datepart(week,convent(datetime(8), imonth+'-'+iday+'-'+iyear,110)=datepart(week,getdate())

Answer 3

select * from 表 where datediff(week,convent(datetime(8), imonth+'-'+iday+'-'+iyear,110),getdate())=0

Answer 4

select * from 表 where datediff(week,convent(datetime(8), cast(imonth as char(4))+'-'+cast(iday as char(2))+'-'+cast(iyear as char(2)),110)=0

Answer 5

select * from testtime where 
datediff(week,cast((cast(iyear as char(4))+'-'+cast(imonth as char(2))
+'-'+cast(iday as char(2)))as datetime),
getdate())=0

Answer 6

select * from testtime where datediff(day,cast((cast(iyear as char(4))+'-'+cast(imonth as char(2))
+'-'+cast(iday as char(2)))as datetime),
getdate())<=7