Very Important Date & time Diff queries in mysql

SELECT TIME_TO_SEC(TIMEDIFF('2007-01-09 10:24:46','2007-01-09 10:23:46'));

SELECT CONCAT(
FLOOR(HOUR(TIMEDIFF(MC.expiry_date,MC.start_date)) / 24), ' days ',
MOD(HOUR(TIMEDIFF(MC.expiry_date,MC.start_date)), 24), ' hours ',
MINUTE(TIMEDIFF(MC.expiry_date,MC.start_date)), ' minutes') as