時間比較:
當前時間是否在某個時間段之內:
是否在create_time+5天之內
select * from message_detail where unix_timestamp(now())
between unix_timestamp(create_time) and unix_timestamp(create_time+ INTERVAL 5 DAY);
是否在last_login+5分鐘之內
select * from user_detail where unix_timestamp('2012-06-29 13:59:21')
between unix_timestamp(last_login) and unix_timestamp(last_login+ INTERVAL 5 MINUTE);