我有一张表可供对比。 该表有一个栏目,名称为<代码>matchdate,即<代码>datetime field。
如果我在2011-12-01年有3个对应点:
- 2011-12-01 12:00:00
- 2011-12-01 13:25:00
- 2011-12-01 16:00:00
我怎么问? 我如何询问所有时间在1个日期是否一致?
I have looked at date_trunc(), to_char(), etc.
Isn t there some "select * where datetime in date" function?
Cast You timestamp 如果你想要简单的条码,则对<条码>的价值。 与此类似:
SELECT *
FROM tbl
WHERE timestamp_col::date = 2011-12-01 ; -- date literal
然而,随着大张表的推移,速度将加快:
SELECT *
FROM tbl
WHERE timestamp_col >= 2011-12-01 0:0 -- timestamp literal
AND timestamp_col < 2011-12-02 0:0 ;
理由:第二点不必改变表格中的每一单项价值,并且能够使用时间段一栏的简单索引。 The expression is sargable 。
Note excluded the upper bound (< instead of <=) for a correct selection.
You can make up for that by creating an index on an expression like this:
CREATE INDEX tbl_ts_date_idx ON tbl (cast(timestamp_col AS date));
然后,第一期问询的速率会越快。
不要确定我是否在这里失踪了明显的东西,但我认为,你只能这样做。
select * from table where date_trunc( day , ts) = 2011-12-01 ;
仅使用BETWEEN这样的功能:
SELECT * FROM table WHERE date BETWEEN 2011-12-01 AND 2011-12-02
你可能需要在字面上注明时间,但这应当包括爱的极限,排除上。
我认为,你可以做:
.where(:between => 2011-12-01 .. 2011-12-02 )
我如何将Excel板的数据输入我的Django应用? I m将PosgreSQL数据库作为数据库。
On production our database is a few hundred gigabytes in size. For development and testing, we need to create snapshots of this database that are functionally equivalent, but which are only 10 or 20 ...
I ll take the simplest of the SQL functions as an example: CREATE OR REPLACE FUNCTION skater_name_match(INTEGER,VARCHAR) RETURNS BOOL AS $$ SELECT $1 IN (SELECT skaters_skater.competitor_ptr_id ...
I m 在当地网络上运行几台机器,在Salgresql8.3处撰写一份申请。
I want to join few attributes in select statement as one for example select id, (name + + surname + + age) as info from users this doesn t work, how to do it? I m using postgreSQL.
Hey, I have 2 tables in PostgreSql: 1 - documents: id, title 2 - updates: id, document_id, date and some data: documents: | 1 | Test Title | updates: | 1 | 1 | 2006-01-01 | | 2 | 1 | 2007-01-01 |...
I need to setup my PostgreSQL DB s text encoding to handle non-American English characters that you d find showing up in languages such as German, Spanish, and French. What character encoding should ...
I am using a set of SQL LIKE conditions to go through the alphabet and list all items beginning with the appropriate letter, e.g. to get all books where the title starts with the letter "A": SELECT * ...