如何从datetime中删除时间 [英] how to remove time from datetime
问题描述
数据库中的DATE字段具有以下格式：
The field DATE in the database has the following format:
2012-11-12 00:00:00
我想从日期删除时间，并返回日期如下：
I would like to remove the time from the date and return the date like this:
11/12/2012
推荐答案
首先是第一件事，如果你的日期是varchar格式的变化，那么将日期存储为日期，它会为您节省很多麻烦，这是最好的做得更早而不是晚了。这个问题只会变得更糟。
First thing's first, if your dates are in varchar format change that, store dates as dates it will save you a lot of headaches and it is something that is best done sooner rather than later. The problem will only get worse.
其次，一旦你有一个日期不要将日期转换为varchar！保留日期格式，并在应用程序方面使用格式来获取所需的日期格式。
Secondly, once you have a date DO NOT convert the date to a varchar! Keep it in date format and use formatting on the application side to get the required date format.
根据您的DBMS有各种各样的方法：
There are various methods to do this depending on your DBMS:
SQL Server 2008 及更高版本：
SQL-Server 2008 and later:
SELECT CAST(CURRENT_TIMESTAMP AS DATE)
SQL-Server 2005 和更早的
SQL-Server 2005 and Earlier
SELECT DATEADD(DAY, DATEDIFF(DAY, 0, CURRENT_TIMESTAMP), 0)
MySQL & SQLite
MySQL & SQLite
SELECT DATE(NOW())
Oracle
SELECT TRUNC(CURRENT_TIMESTAMP)
Postgresql
SELECT CURRENT_TIMESTAMP::DATE
如果您需要在报告中使用文化特定格式，您可以明确说明接收文本框的格式（例如，dd / MM / yyyy），也可以设置语言，以显示该语言的相关日期格式。
If you need to use culture specific formatting in your report you can either explicitly state the format of the receiving text box (e.g. dd/MM/yyyy), or you can set the language so that it shows the relevant date format for that language.
无论哪种方式在SQL之外处理得更好，因为在SQL中转换为varchar会影响您在报告中可能执行的任何排序。
Either way this is much better handled outside of SQL as converting to varchar within SQL will impact any sorting you may do in your report.
如果您不能/不会将数据类型更改为DATETIME，则sti将其转换为SQL内的日期（例如， CONVERT（DATETIME，yourField）），然后发送到报告服务并按照上述处理。
If you cannot/will not change the datatype to DATETIME, then still convert it to a date within SQL (e.g. CONVERT(DATETIME, yourField)) before sending to report services and handle it as described above.
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