Oracle Database INTERVAL DAY TO SECOND type use

INTERVAL DAY TO SECOND type units can be used to store the second time interval days. The following statement creates a table called promotions used to store promotions. promotions table contains a INTERVAL DAY TO SECOND type columns duration, the column for recording promotional effective time interval:

 CREATE TABLE promotions (
promotion_id INTEGER CONSTRAINT promotions_pk PRIMARY KEY,
name VARCHAR2(30) NOT NULL,
duration INTERVAL DAY(3) TO SECOND (4)
);

Note that the accuracy of the fractional part is specified here transit accuracy duration column 3, 4 seconds. That number can be three day storage for the column, the second column for storing up to 4 digits to the right of the decimal point.

To provide a INTERVAL DAY TO SECOND literal database, you can use the following simplified syntax:

INTERVAL '[+|-][ d] [ h[: m[: s]]]' [DAY[( days_precision)]])
[TO HOUR | MINUTE | SECOND[( seconds_precision)]]

among them

● + or - is an optional indicator for explaining the time interval is positive or negative (the default is a positive number).

● d is the number of days interval.

● h is an optional parameter indicating the number of hours interval. If the designated days and hours, must be included in the TO HOUR INTERVAL clause.

● h is an optional parameter indicating the number of minute interval. If you specify days and hours, it must be included in the TO MINUTES INTERVAL clause.

● s is an optional parameter indicating the number of seconds of the time interval. If you specify days and seconds, it must be included in the TO SECOND INTERVAL clause.

● days_precision is an optional parameter for tomorrow with precision number (the default is 2).

● seconds_precision is an optional parameter used to describe the accuracy of seconds (default 6).

TABLE 5-12 gives several examples of type INTERVAL DAY TO SECOND interval literal.

Examples 5-12 Table interval literals

Interval literals	Explanation
INTERVAL ‘3’ DAY	Interval of 3 days
INTERVAL ‘2’ HOUR	Time is 2 hours
INTERVAL ‘25’ MINUTE	The time interval of 25 minutes
INTERVAL ‘45’ SECOND	Interval 45 seconds
INTERVAL ‘3 2’ DAY TO HOUR	Interval to 3 days and 2 hours
INTERVAL ‘3 2:25’ DAY TO MINUTE	Interval to 3 days and 2 hours 25 minutes
INTERVAL ‘3 2:25:45’ DAY TO SECOND	Interval to 3 days and 2 hours 25 minutes 45 seconds
INTERVAL ‘123 2:25:45.12’ DAY(3) TO SECOND(2)	Interval of 123 days and 2 hours 25 minutes 45.12 seconds; accuracy day 3 digits, the accuracy of fractions of a second digit is 2
INTERVAL ‘3 2:00:45’ DAY TO SECOND	Interval of 3 days 2 hours 0 minutes 45 seconds
INTERVAL ‘-3 2:25:45’ DAY TO SECOND	Interval is negative, a value of 3 days and 2 hours 25 minutes 45 seconds
INTERVAL ‘1234 2:25:45’ DAY(3) TO SECOND	The time interval is not valid because the median days exceeds the specified accuracy of 3
INTERVAL ‘123 2:25:45.123’ DAY TO SECOND(2)	Invalid intervals, because the number of fractional digits exceeds the second specified precision 2

The following INSERT statement adds a row to the table promotions:

 INSERT INTO promotions (promotion_id, name, duration)
VALUES (1, '10% off Z Files', INTERVAL '3' DAY);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (2, '20% off Pop 3', INTERVAL '2' HOUR);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (3, '30% off Modern Science', INTERVAL '25' MINUTE);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (4, '20% off Tank War', INTERVAL '45' SECOND);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (5, '10% off Chemistry', INTERVAL '3 2:25' DAY TO MINUTE);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (6, '20% off Creative Yell', INTERVAL '3 2:25:45' DAY TO SECOND);

INSERT INTO promotions (promotion_id, name, duration)
VALUES (7, '15% off My Front Line',
INTERVAL '123 2:25:45.12' DAY(3) TO SECOND(2));

下面这个查询对promotions表进行检索，注意duration列值的格式化：

 SELECT *
FROM promotions;

PROMOTION_ID  NAME                              DURATION
------------ ------------------------------   ------------------
1   10% off Z Files                  +003 00:00:00.0000
2   20% off Pop 3                    +000 02:00:00.0000
3   30% off Modern Science           +000 00:25:00.0000
4   20% off Tank War                 +000 00:00:45.0000
5   10% off Chemistry                +003 02:25:00.0000
6   20% off Creative Yell            +003 02:25:45.0000
7   15% off My Front Line            +123 02:25:45.1200

INTERVAL DAY TO SECOND类型可以用来存储单位为天和秒的时间间隔。下面这条语句创建一个名为promotions的表，用来存储促销信息。promotions表包含了一个INTERVAL DAY TO SECOND类型的列duration，该列用来记录促销有效的时间间隔：

 CREATE TABLE promotions (
promotion_id INTEGER CONSTRAINT promotions_pk PRIMARY KEY,
name VARCHAR2(30) NOT NULL,
duration INTERVAL DAY(3) TO SECOND (4)
);

注意此处指定了duration列中天的精度为3，秒的小数部分精度为4。这就是说可以为该列的天存储3位数字，而为该列的秒最多可以在小数点右边存储4位数字。

要向数据库提供一个INTERVAL DAY TO SECOND字面值，可以使用下面的简化语法：

INTERVAL '[+|-][ d] [ h[: m[: s]]]' [DAY[( days_precision)]])
[TO HOUR | MINUTE | SECOND[( seconds_precision)]]

其中

● + 或 - 是一个可选的指示符，用来说明时间间隔是正数还是负数(默认为正数)。

● d 是时间间隔的天数。

● h 是一个可选参数，表示时间间隔的小时数。如果指定了天和小时，必须在INTERVAL子句中包含TO HOUR。

● h 是一个可选参数，表示时间间隔的分钟数。如果指定了天和分，必须在INTERVAL子句中包含TO MINUTES。

● s 是一个可选参数，表示时间间隔的秒数。如果指定了天和秒，必须在INTERVAL子句中包含TO SECOND。

● days_precision是一个可选参数，用来说明天数的精度(默认值为2)。

● seconds_precision是一个可选参数，用来说明秒的精度(默认值为6)。

表5-12给出了几个INTERVAL DAY TO SECOND类型的时间间隔字面量的例子。

表5-12 时间间隔字面量的例子

时间间隔字面量	说明
INTERVAL ‘3’ DAY	时间间隔为3天
INTERVAL ‘2’ HOUR	时间间隔为2小时
INTERVAL ‘25’ MINUTE	时间间隔为25分钟
INTERVAL ‘45’ SECOND	时间间隔为45秒
INTERVAL ‘3 2’ DAY TO HOUR	时间间隔为3天零2小时
INTERVAL ‘3 2:25’ DAY TO MINUTE	时间间隔为3天零2小时25分
INTERVAL ‘3 2:25:45’ DAY TO SECOND	时间间隔为3天零2小时25分45秒
INTERVAL ‘123 2:25:45.12’ DAY(3) TO SECOND(2)	时间间隔为123天零2小时25分45.12秒；天的精度是3位数字，秒的小数部分的精度是2位数字
INTERVAL ‘3 2:00:45’ DAY TO SECOND	时间间隔为3天2小时0分45秒
INTERVAL ‘-3 2:25:45’ DAY TO SECOND	时间间隔为负数，值为3天零2小时25分45秒
INTERVAL ‘1234 2:25:45’ DAY(3) TO SECOND	时间间隔无效，因为天的位数超过了指定的精度3
INTERVAL ‘123 2:25:45.123’ DAY TO SECOND(2)	时间间隔无效，因为秒的小数部分的位数超过了指定的精度2

下面这个INSERT语句向promotions表添加一行记录：

 INSERT INTO promotions (promotion_id, name, duration)
VALUES (1, '10% off Z Files', INTERVAL '3' DAY);