oracle 添加day/hour/minute/second到一个DATE类型数据中

The SYSDATE pseudo-column shows the current system date and time. Adding 1 to SYSDATE will advance the date by 1 day. Use fractions to add hours, minutes or seconds to the date. Look at these examples:

SQL> select sysdate, sysdate+1/24, sysdate +1/1440, sysdate + 1/86400 from dual;

SYSDATE              SYSDATE+1/24         SYSDATE+1/1440       SYSDATE+1/86400
-------------------- -------------------- -------------------- --------------------
03-Jul-2002 08:32:12 03-Jul-2002 09:32:12 03-Jul-2002 08:33:12 03-Jul-2002 08:32:13

The following format is frequently used with Oracle Replication:

select sysdate NOW, sysdate+30/(24*60*60) NOW_PLUS_30_SECS from dual;

NOW                  NOW_PLUS_30_SECS
-------------------- --------------------
03-JUL-2005 16:47:23 03-JUL-2005 16:47:53

Here are a couple of examples:

Description	Date Expression
Now	SYSDATE
Tomorow/ next day	SYSDATE + 1
Seven days from now	SYSDATE + 7
One hour from now	SYSDATE + 1/24
Three hours from now	SYSDATE + 3/24
An half hour from now	SYSDATE + 1/48
10 minutes from now	SYSDATE + 10/1440
30 seconds from now	SYSDATE + 30/86400
Tomorrow at 12 midnight	TRUNC(SYSDATE + 1)
Tomorrow at 8 AM	TRUNC(SYSDATE + 1) + 8/24
Next Monday at 12:00 noon	NEXT_DAY(TRUNC(SYSDATE), 'MONDAY') + 12/24
First day of the month at 12 midnight	TRUNC(LAST_DAY(SYSDATE ) + 1)
The next Monday, Wednesday or Friday at 9 a.m	TRUNC(LEAST(NEXT_DAY(sysdate,''MONDAY' ' ),NEXT_DAY(sysdate,''WEDNESDAY''), NEXT_DAY(sysdate,''FRIDAY'' ))) + (9/24)