oracle 在原有的时间上加一天，加一个小时，加一分钟

1. select to_date('02-22-2008 10:30:30','mm-dd-yyyy hh24:mi:ss') today,
   to_date('02-22-2008 10:30:30','mm-dd-yyyy hh24:mi:ss')+1 next_day
   from dual;
   TODAY  NEXT_DAY
   ------------------------- -------------------------
   02-22-08 10:30:30 02-23-08 10:30:30
2. Add an hour.
   select to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss') today,
   to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss')+ 1/24 next_hour
   from dual;
   TODAY  NEXT_HOUR
   ------------------------ ------------------------
   02-22-08 10:30:30 02-22-08 11:30:30
3. Add a minute.
   select to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss') today,
   to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss')+ 1/(24*60) next_min
   from dual;
   TODAY  NEXT_MIN
   ------------------------ ------------------------
   02-22-08 10:30:30 02-22-08 10:31:30
4. Add a second.
   select to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss') today,
   to_date('02-22-08 10:30:30','mm-dd-yy hh24:mi:ss')+ 1/(24*60*60) next_sec
   from dual;
   TODAY  NEXT_SEC
   ------------------------ ------------------------
   02-22-08 10:30:30 02-22-08 10:30:31