SQL 从 PostgreSQL 的时间戳中提取日期 (yyyy/mm/dd)
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/6133107/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Extract date (yyyy/mm/dd) from a timestamp in PostgreSQL
提问by keren
I want to extract just the date part from a timestamp in PostgreSQL.
我只想从 PostgreSQL 的时间戳中提取日期部分。
I need it to be a postgresql DATEtype so I can insert it into another table that expects a DATEvalue.
我需要它是 postgresqlDATE类型，以便我可以将它插入到另一个需要DATE值的表中。
For example, if I have 2011/05/26 09:00:00, I want 2011/05/26
例如，如果我有2011/05/26 09:00:00，我想要2011/05/26
I tried casting, but I only get 2011:
我试过铸造，但我只得到 2011 年：
timestamp:date
cast(timestamp as date)
I tried to_char()with to_date():
我试着to_char()用to_date()：
SELECT to_date(to_char(timestamp, 'YYYY/MM/DD'), 'YYYY/MM/DD')
FROM val3 WHERE id=1;
I tried to make it a function:
我试图使它成为一个函数：
CREATE OR REPLACE FUNCTION testing() RETURNS void AS '
DECLARE i_date DATE;
BEGIN
SELECT to_date(to_char(val1, "YYYY/MM/DD"),"YYYY/MM/DD")
INTO i_date FROM exampTable WHERE id=1;
INSERT INTO foo(testd) VALUES (i);
END
What is the best way to extract date (yyyy/mm/dd) from a timestamp in PostgreSQL?
从 PostgreSQL 的时间戳中提取日期 (yyyy/mm/dd) 的最佳方法是什么？
回答by Wayne Conrad
You can cast your timestamp to a date by suffixing it with ::date. Here, in psql, is a timestamp:
您可以通过添加后缀将时间戳转换为日期::date。这里，在 psql 中，是一个时间戳：
# select '2010-01-01 12:00:00'::timestamp;
timestamp
---------------------
2010-01-01 12:00:00
Now we'll cast it to a date:
现在我们将它投射到一个日期：
wconrad=# select '2010-01-01 12:00:00'::timestamp::date;
date
------------
2010-01-01
On the other hand you can use date_truncfunction. The difference between them is that the latter returns the same data type like timestamptzkeeping your time zone intact (if you need it).
另一方面，您可以使用date_trunc函数。它们之间的区别在于后者返回相同的数据类型，例如timestamptz保持时区完整（如果需要）。
=> select date_trunc('day', now());
date_trunc
------------------------
2015-12-15 00:00:00+02
(1 row)
回答by James Allman
Use the datefunction:
使用日期函数：
select date(timestamp_field) from table
From a character field representation to a date you can use:
从字符字段表示到日期，您可以使用：
select date(substring('2011/05/26 09:00:00' from 1 for 10));
Test code:
测试代码：
create table test_table (timestamp_field timestamp);
insert into test_table (timestamp_field) values(current_timestamp);
select timestamp_field, date(timestamp_field) from test_table;
Test result:
测试结果：
回答by leonbloy
Have you tried to cast it to a date, with <mydatetime>::date?
您是否尝试将其转换为日期<mydatetime>::date？
回答by thedarkgriffen
This works for me in python 2.7
这在 python 2.7 中对我有用
select some_date::DATE from some_table;
回答by Koushik Das
Just do select date(timestamp_column)and you would get the only the date part.
Sometimes doing select timestamp_column::datemay return date 00:00:00where it doesn't remove the 00:00:00part. But I have seen date(timestamp_column)to work perfectly in all the cases. Hope this helps.
只要这样做select date(timestamp_column)，你就会得到唯一的日期部分。有时这样做select timestamp_column::date可能会返回date 00:00:00它没有移除00:00:00零件的地方。但我已经看到date(timestamp_column)在所有情况下都能完美地工作。希望这可以帮助。
回答by Grzegorz Szpetkowski
CREATE TABLE sometable (t TIMESTAMP, d DATE);
INSERT INTO sometable SELECT '2011/05/26 09:00:00';
UPDATE sometable SET d = t; -- OK
-- UPDATE sometable SET d = t::date; OK
-- UPDATE sometable SET d = CAST (t AS date); OK
-- UPDATE sometable SET d = date(t); OK
SELECT * FROM sometable ;
t | d
---------------------+------------
2011-05-26 09:00:00 | 2011-05-26
(1 row)
Another test kit:
另一个测试套件：
SELECT pg_catalog.date(t) FROM sometable;
date
------------
2011-05-26
(1 row)
SHOW datestyle ;
DateStyle
-----------
ISO, MDY
(1 row)
回答by Elmira Behzad
In postgres simply : TO_CHAR(timestamp_column, 'DD/MM/YYYY') as submission_date
在 postgres 中简单地：TO_CHAR(timestamp_column, 'DD/MM/YYYY') 作为 submit_date
