If I have a table full of Ages, and want to calculate their ages. This is the sure way to do it.
I have tried doing it other ways, and it has been fraught with errors that creep in with things like leap years, months with different numbers of days, etc.
But once, I was lucky enough to work with a good SQL Guru, and he taught me this.
,DateDiff(YY, I.BirthDate, GetDate())
Then 1 Else 0
End As [Age]