I ran across this terrific resource, Common MySQL Queries.
Tons of great examples…for example:
Given a birthdate in @dob, here are two simple formulae for age in years:
Date_format( From_Days( To_Days(Curdate()) - To_Days(@dob) ), '%Y' ) + 0 Year(Curdate()) - Year(@dob) - ( Right(Curdate(),5) < Right(@dob,5) )
and here is one for age in years to two decimal places, ignoring day of month:
Round((((Year(now()) - Year(@dob)))*12 + (((Month(now()) - Month(@dob)))))/12, 2)
Enjoy!