时间字段在SQL语句中如何运算？

Question

select  *  form table   where  DATEDIFF ( minute , LastAccessTime , getdate() )=30

Answer 1

select * from tb where  datediff(mi,LastAccessTime,getdate())>30

Answer 2

或者
select * from tb where  datediff(mi,getdate(),LastAccessTime)>30

Answer 3

select * from tb where  datediff(mi,getdate(),LastAccessTime)<30

Answer 4

select * from tb where  datediff(mi,LastAccessTime,getdate())>30

Answer 5

select * from tb where  datediff(mi,LastAccessTime,getdate())>30

Answer 6

select * 
from tb 
where abs( datediff ( mi, LastAccessTime, GetDate() ) ) > 30

Answer 7

select * from tb where datediff(mi,LastAccessTime,GetDate())) > 30