SELECT CEIL((UNIX_TIMESTAMP(‘2011-05-31 23:59:59‘) - UNIX_TIMESTAMP(‘2011-05-31 00:59:59‘))/1000/60/60);

UNIX_TIMESTAMP(‘2011-05-31 23:59:59‘)//时间转换成毫秒

 SELECT FROM_UNIXTIME(1306771200);  //毫秒转换成时间

ceil()整数取整

mysql 字符串转换呈毫秒值