INTERVAL的使用

INTERVAL可以用来做时间的加减法：

SELECT INTERVAL '300' MONTH "25年",

       INTERVAL '54-2' YEAR TO MONTH "54年2个月",

       INTERVAL '11:12:10.1234567' hour TO SECOND "小时到秒"

FROM dual;

语法:

INTERVAL '{ integer | integer time_expr | time_expr }'

{ { DAY | HOUR | MINUTE } [ ( leading_precision ) ]

| SECOND [ ( leading_precision [, fractional_seconds_precision ] ) ] }

[ TO { DAY | HOUR | MINUTE | SECOND [ (fractional_seconds_precision) ] } ]

示例：

SQL> select date '2010-01-01' + interval '21' year from dual;

DATE'2010-01-01'+INTERVAL'21'Y

------------------------------

2031-01-01

SQL> select date '2010-01-01' + interval '123-2' year(4) to month from dual;

DATE'2010-01-01'+INTERVAL'123-

------------------------------

2133-03-01

SQL> select date '2010-01-01' + interval '100' month from dual;

DATE'2010-01-01'+INTERVAL'100'

------------------------------

2018-05-01

SQL> select date '2010-01-01' + interval '100' day(2) from dual;

select date '2010-01-01' + interval '100' day(2) from dual

ORA-01873: the leading precision of the interval is too small --这里应该是day(3) 因为interval之后的100是三位数，默认是2位数

SQL> select date '2010-01-01' + interval '1 2' day to hour from dual;

DATE'2010-01-01'+INTERVAL'12'D

------------------------------

2010-01-02 02:00:00

SQL> select date '2010-01-01' + interval '1 2:3' day to minute from dual;

DATE'2010-01-01'+INTERVAL'12:3

------------------------------

2010-01-02 02:03:00

SQL> select date '2010-01-01' + interval '1 2:3:4' day to second from dual;

DATE'2010-01-01'+INTERVAL'12:3

------------------------------

2010-01-02 02:03:04

SQL> select date '2010-01-01' + interval '1' hour from dual;

DATE'2010-01-01'+INTERVAL'1'HO

------------------------------

2010-01-01 01:00:00

SQL> select date '2010-01-01' + interval '1:2' hour to minute from dual;

DATE'2010-01-01'+INTERVAL'1:2'

------------------------------

2010-01-01 01:02:00

SQL> select date '2010-01-01' + interval '1:2:3' hour to second from dual;

DATE'2010-01-01'+INTERVAL'1:2:

------------------------------

2010-01-01 01:02:03

SQL> select date '2010-01-01' + interval '1:2' minute to second from dual;

DATE'2010-01-01'+INTERVAL'1:2'

------------------------------

2010-01-01 00:01:02