Simple do one thing that when ever any user came, Check if the Date part of users equals to today system date. Here is the query
Select Name from User where DATEADD(D, 0, DATEDIFF(D, 0, DOB)) = DATEADD(D, 0, DATEDIFF(D, 0, '1989-01-08 00:00:00.000'))
Here 'DATEADD(D, 0, DATEDIFF(D, 0, DOB))' express results in matching the date part only.
All the best!!