Retrieving All Users In Db With Specified AGE Range

Hello, I have a table called Member in my database that I use to store information about users including the date of birth for each person.  I have a search function in my application that is supposed to look through the Member table and spit out a list of users with a user-inputted age range (min and max ages).  Now, I could have stored ages instead of dob in the table, but I would think that's bad practice since age changes and would need continuous recomputing (which is db intensive) as opposed to dob which stays the same.

So what I'm thinking is getting the min and max user inputted ages, convert them to dob values (of type DateTime) in the application.  And then, to query the db and return a list of all users in the Member whose dob falls in between those two dates (is a BETWEEN even possible with DateTime values?).

How is the best way to go about this?  There are many sites out there that return users with user specified age ranges.  Is there a best way to do this that's the least taxing on the db?

TIA.