My MySQL database has date of birth stored in the format yyyy-mm-dd, how do I query the database - without using php code - to show me results of people born within x years of now, and/or, who are y years of age?

The table is called users, the colum is called dob. I've spent a while viewing the MySQL manual but I can't work out precisely how to form my query.

So far I went for select * from users where dob... but I don't think that's the way to go.