Calculate Age from Database in MySQL

This function can be used to calculate age.

DELIMITER $$

DROP FUNCTION IF EXISTS Age $$

CREATE FUNCTION Age( dob DATE )
RETURNS CHAR(20)
BEGIN
DECLARE years INT default 0;
DECLARE months INT default 0;
DECLARE days INT default 0;
DECLARE age DATE;

-- Check that the dob we're given is useful
IF dob is null or dob = 0 or dob = '0000-00-00' THEN
 RETURN dob;
END IF;
SELECT date_add('0001-01-01', interval datediff(current_date(),dob) day ) INTO age;
SELECT YEAR(age) -1 INTO years;
SELECT MONTH(age)-1 INTO months;
SELECT DAY(age) -1 INTO days;

IF years THEN
 RETURN concat(years,'y ',months,'m');
ELSEIF months THEN
 RETURN concat(months,'m ',days,'d');
ELSE
 RETURN concat(days,' days');
END IF;
END $$
DELIMITER ;

Use

SELECT Age(DOB) FROM table; 

Source : http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html

Validating Form Input

This function strips unwanted characters (extra space, tab, newline) from the beginning and end of the data using the PHP trim() function, strips any quotes escaped with slashes and passes it through htmlspecialchars().

function checkInput($data) {
    $data = trim($data);
    $data = stripslashes($data);
    $data = htmlspecialchars($data);
    return $data;
}

Use

checkInput($_POST['postdata']); 
checkInput($_GET['getdata']);