MySQL DATE_SUB Function

If you are using a database as the back-end, programmers needs to access data from the databases (i.e. MySQL) and process them before display information to the clients. For example if you have date of Birth (dob) in a database table column, you need to read each dob from the table and calculate the age inside your coding.
If you are using MySQL, it allows you to do small calculations with your queries.

DATE_SUB / DATE_ADD are very useful MySQL functions which reduce more coding in your program.

Following given is one example of using DATE_SUB function.

$query = "select customer.name as name, orig_date from where orig_date > DATE_SUB(CURDATE(),INTERVAL 7 DAY)
This will display the records created within one week time

Good Reference
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html