setting it up to limit it to the current month if in a calendar type view. or if you are querying for each day that is rendered a statement to limit it to that day of that month
Not quite sure exactly what you're looking for, but...
For displaying people celebrating their birthday today (with their age):
PHP Code:
SELECT cname,dob,YEAR(NOW())-YEAR(dob) AS age FROM <table> WHERE DAYOFYEAR(dob) = DAYOFYEAR(NOW());
// Returns 28 as `age` when the current date is 2010-09-12
Simply display the next birthday of an individual person:
PHP Code:
SELECT MAKEDATE(YEAR(NOW()), DAYOFYEAR(dob)) AS next_bday FROM <table> WHERE cname='<name>';
// Returns 2010-09-12 as `next_bday` for a dob of 9/12/1982