大约有 44,000 项符合查询结果（耗时：0.0388秒） [XML]
Regular expression to allow spaces between words
...
tl;dr
Just add a space in your character class.
^[a-zA-Z0-9_ ]*$
Now, if you want to be strict...
The above isn't exactly correct. Due to the fact that * means zero or more, it would match all of the following cases that one would not usually mea...
Aggregate / summarize multiple variables per group (e.g. sum, mean)
...-date), sum)
# summarising a specific set of non-grouping variables using select_helpers
# see ?select_helpers for more options
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(starts_with('x')), sum)
df2 <- df1 %>% group_by(year, month) %>% summarise_at(vars(matches('.*...
How to add extra info to copied web text
...cument.location.href}`;
event.clipboardData.setData('text', document.getSelection() + pagelink);
event.preventDefault();
});
Lorem ipsum dolor sit amet, consectetur adipiscing elit.<br/>
<textarea name="textarea" rows="7" cols="50" placeholder="paste your copied text here"></...
How do I query between two dates using MySQL?
...ember 29 2010 and January 30 2010). Try reversing the order of the dates:
SELECT *
FROM `objects`
WHERE (date_field BETWEEN '2010-01-30 14:15:55' AND '2010-09-29 10:15:55')
share
|
improve this an...
How do I add a library project to Android Studio?
..., go to Project Structure -> under Modules just hit the plus button and select Import Existing Project and import actionbarsherlock. Then synchronise your Gradle files.
If you face the error
Error: The SDK Build Tools revision (xx.x.x) is too low. Minimum
required is yy.y.y
just open the...
Count number of records returned by group by
...
You can do both in one query using the OVER clause on another COUNT
select
count(*) RecordsPerGroup,
COUNT(*) OVER () AS TotalRecords
from temptable
group by column_1, column_2, column_3, column_4
share
...
How to select date from datetime column?
...ry.
Use BETWEEN or >, <, = operators which allow to use an index:
SELECT * FROM data
WHERE datetime BETWEEN '2009-10-20 00:00:00' AND '2009-10-20 23:59:59'
Update: the impact on using LIKE instead of operators in an indexed column is high. These are some test results on a table with 1,...
Insert all values of a table into another table in SQL
.... But the insert statement accepts values, but i would like it to accept a select * from the initial_Table. Is this possible?
...
记一次数据库表自增长（Auto Increment）故障 - 数据库(内核) - 清泛网 - ...
...么我们不妨换个思路，显式设置唯一标识，比如说通过「SELECT MAX … FOR UPDATE」的方式直接查询得到唯一标识符，并在稍后执行的 INSERT 语句中显式设置。
不过这种方法不够透明，需要修改业务代码，更透明的方法是使用触发器...
HTTPS with Visual Studio's built-in ASP.NET Development Server
...
Select the project-file in the Solution Explorer: for example: "WebApplication1".
With pressing ALT+ENTER you enter the project-properties.
Select "DEBUG" on the left side.
Here you can select "Enable SSL".
Then you can...