interval usage in oracle

The INTERVAL type in Oracle is used to represent a time period, including time units (such as days, hours) and time quantities (such as 3, 10); it is often used to calculate the difference between date or time values. The syntax is INTERVAL time_value time_unit, where time_value is the time quantity and time_unit is the time unit, such as YEAR, MONTH, DAY, etc.; for example, calculate the number of days between two dates: SELECT INTERVAL '2023-06-15' - '2023-05 -15' DAY FROM DUAL;

INTERVAL type in Oracle

INTERVAL type is used to represent a time period or Date range. It contains the following two parts:

• Time unit (for example, days, hours, minutes)
• Time quantity (for example, 3, 10, 50)

Usage

INTERVAL type is generally used to calculate the difference between date or time values. The syntax is as follows:

<code>INTERVAL time_value time_unit</code>

Where:

• time_value is the time quantity, which can be a positive or negative number.

• time_unit is the time unit and can be the following values:

  • YEAR
  • MONTH
  • ##DAY
  • HOUR
  • MINUTE
  • SECOND

Example

The following example shows some uses of the INTERVAL type:

<code>-- 计算两个日期之间的天数
SELECT INTERVAL '2023-06-15' - '2023-05-15' DAY FROM DUAL;</code>

Output:

<code>31</code>

<code>-- 计算当前时间到指定时间的分钟数
SELECT INTERVAL TIMESTAMP '2023-06-15 10:30:00' - CURRENT_TIMESTAMP MINUTE FROM DUAL;</code>

Output:

<code>25</code>

<code>-- 根据天数创建一个 INTERVAL
SELECT INTERVAL 30 DAY FROM DUAL;</code>

Output:

<code>30 DAY</code>

Notes

INTERVAL type cannot be directly used with Date or time values ​​are compared.
• The precision of the INTERVAL type depends on the time unit. For example, 1 DAY is more precise than 1 HOUR.
• When using the INTERVAL type, ensure that the time unit matches the calculated difference.

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