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📜  PostgreSQL日期时间

📅  最后修改于: 2020-12-01 00:54:22             🧑  作者: Mango

PostgreSQL日期和时间功能

与日期和时间相关的所有重要功能的列表：

Function Description
AGE() Subtract arguments
CURRENT DATE/TIME() It specifies current date and time.
DATE_PART() Get subfield (equivalent to extract)
EXTRACT() Get subfield.
ISFINITE() Test for finite date ,time and interval (not +/-infinity)
JUSTIFY Adjust interval

AGE(时间戳，时间戳)和AGE(时间戳)：

function description
age(timestamp, timestamp) when invoked with the timestamp form of the second argument, age() subtract arguments, producing a “symbolic” result that uses years and months and is of type interval.
age(timestamp) when invoked with only the timestamp as argument, age() subtracts from the current_date (at midnight).

让我们以一个示例检查AGE(timestamp，timestamp)查询为例。

请参阅以下示例：

通过按Ctrl + E打开查询页面。

执行此查询：

SELECT AGE(时间戳'2016-01-26'，时间戳'1947-08-15');

函数AGE(timestamp)的示例是：

它用于产生当前年龄。

执行以下查询：

SELECT AGE(时间戳'1947-08-15');

当前DATE / TIME()

以下是返回与当前日期和时间相关的值的函数列表。

Function Description
CURRENT_DATE Delivers current date.
CURRENT_TIME Delivers values with time zone.
CURRENT_TIMESTAMP Delivers values with time zone.
CURRENT_TIME(precision) Optionally takes a precision parameter, which causes the result to be rounded to that many fractional digits in the seconds field.
CURRENT_TIMESTAMP(precision) Optionally takes a precision parameter, which causes the result to be rounded to that many fractional digits in the seconds field.
LOCALTIME Delivers values without time zone.
LOCALTIMESTAMP Delivers values without time zone.
LOCALTIME(precision) Optionally takes a precision parameter, which causes the result to be rounded to that many fractional digits in the seconds field.
LOCALTIMESTAMP(precision) Optionally takes a precision parameter, which causes the result to be rounded to that many fractional digits in the seconds field.

现在，您可以检查以下命令：

当前时间：

SELECT CURRENT_TIME;

对于当前日期：

SELECT CURRENT_DATE;

对于当前时间戳(日期和时间都)

SELECT CURRENT_TIMESTAMP;

当前时间戳更加精确：

SELECT CURRENT_TIMESTAMP(2);

本地时间戳记：

SELECT LOCALTIMESTAMP;