大约有 40,000 项符合查询结果（耗时：0.0241秒） [XML]
How to get the instance id from within an ec2 instance?
...me up with: At the end of the line ($), find one or more digits following by one or more lowercase letters. Substitute with the digits only. (Backslash + parentheses tell sed to remember a substring, which is recalled with \1.) I found this a little easier to read--the only backslashes are those r...
How to use GROUP BY to concatenate strings in MySQL?
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SELECT id, GROUP_CONCAT(name SEPARATOR ' ') FROM table GROUP BY id;
http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
From the link above, GROUP_CONCAT: This function returns a string result with the concatenated non-NULL values from a group. It re...
For each row return the column name of the largest value
...ong putting all the departments in one column and counts in another, group by the employer id (in this case, the row number), and then filter to the department(s) with the max value. There are a couple of options for handling ties with this approach too.
library(tidyverse)
# sample data frame with...
Which is fastest? SELECT SQL_CALC_FOUND_ROWS FROM `table`, or SELECT COUNT(*)
When you limit the number of rows to be returned by a SQL query, usually used in paging, there are two methods to determine the total number of records:
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javascript find and remove object in array based on key value
... id, but how can I delete the entire object where id == 88
Simply filter by the opposite predicate:
var data = $.grep(data, function(e){
return e.id != id;
});
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find() with nil when there are no records
...
Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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selecting unique values from a column
... DISTINCT operator in MySQL:
SELECT DISTINCT(Date) AS Date FROM buy ORDER BY Date DESC;
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How do I get jQuery to select elements with a . (period) in their ID?
...elect(data);
});
});
});
Also check out How do I select an element by an ID that has characters used in CSS notation? on the jQuery FAQ.
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Sample settings.xml for maven
...icense at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing,
software distributed under the License is distributed on an
"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
KIND, either express or implied. See the License for the
specific ...
How to get last N records with activerecord?
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Updated Answer (2020)
You can get last N records simply by using last method:
Record.last(N)
Example:
User.last(5)
Returns 5 users in descending order by their id.
Deprecated (Old Answer)
An active record query like this I think would get you what you want ('Something' is the mode...