date difference, current date in mysql

Reference: Date and time functions in MySQL 5.1

DATEDIFF() returns expr1 – expr2 expressed as a value in days from one date to the other. expr1 and expr2 are date or date-and-time expressions. Only the date parts of the values are used in the calculation.

mysql> SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30');
       -> 1
mysql> SELECT DATEDIFF('2010-11-30 23:59:59','2010-12-31');
       -> -31

CURDATE()

Returns the current date as a value in 'YYYY-MM-DD' or YYYYMMDD format, depending on whether the function is used in a string or numeric context.

mysql> SELECT CURDATE();
       -> '2008-06-13'
mysql> SELECT CURDATE() + 0;
       -> 20080613