PostgreSQL等同于Oracle的SYSDATE?

问题描述

我想使用sysdate执行查询，例如:

I want to perform a query using sysdate like:

select up_time from exam where up_time like sysdate

这在Oracle中是可能的.

which is possible in Oracle.

但是，似乎PostgreSQL不支持sysdate.我在postgres文档中找不到sysdate. PostgreSQL中sysdate的替代品是什么?

However, it seems that PostgreSQL doesn't support sysdate. I couldn't find sysdate in postgres documentation. What is the replacement for sysdate in PostgreSQL?

推荐答案

SYSDATE是仅Oracle的函数.

SYSDATE is an Oracle only function.

Postgres支持ANSI标准的current_date或current_timestamp，并在手册中进行了记录:
http://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT

The ANSI standard defines current_date or current_timestamp which is supported by Postgres and documented in the manual:
http://www.postgresql.org/docs/current/static/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT

(顺便说一句:Oracle也支持CURRENT_TIMESTAMP)

(Btw: Oracle supports CURRENT_TIMESTAMP as well)

您应注意current_timestamp，statement_timestamp()和clock_timestamp()之间的区别(在手册中进行了说明，请参见上面的链接)

You should pay attention to the difference between current_timestamp, statement_timestamp() and clock_timestamp() (which is explained in the manual, see the above link)

此声明:

完全没有任何意义.在Oracle和Postgres中都没有.如果要从今天"获取行，则需要类似以下内容的

Does not make any sense at all. Neither in Oracle nor in Postgres. If you want to get rows from "today", you need something like:

select up_time
from exam
where up_time = current_date

请注意，在Oracle中，您可能希望trunc(up_time) = trunc(sysdate)摆脱Oracle中始终包含的时间部分.

Note that in Oracle you would probably want trunc(up_time) = trunc(sysdate) to get rid of the time part that is always included in Oracle.

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