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Using LIMIT within GROUP BY to get N results per group?
... behavior of both quirks is not guaranteed. Revised answer as follows.
In MySQL 5.x you can use poor man's rank over partition to achieve desired result. Just outer join the table with itself and for each row, count the number of rows lesser than it. In the above case, lesser row is the one with hi...
MongoDB with redis
...od results. A company well-known for running MongoDB and Redis (along with MySQL and Sphinx) is Craiglist. See this presentation from Jeremy Zawodny.
MongoDB is interesting for persistent, document oriented, data indexed in various ways. Redis is more interesting for volatile data, or latency sensi...
SecurityException: Permission denied (missing INTERNET permission?)
...things are getting more tricky if you also do not mind your app running on rooted devices too. There're tools available in Google Play your users can install to control permission granted to installed apps at run-time - for example: Permissions Denied and others. This can also be done with CyanogenM...
使用 JSON 和 Web API · App Inventor 2 中文网
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响应内容：服务器返回的响应内容为文本，让我们看看如何将其作为JSON进行处理：
Web客户端组件提供了方法将JSON文本解码为字典 获取文本的内容，比如 响应内容 参数，并将其转换为适当的 App Inventor 类型。根据返回的内...
What is the email subject length limit?
...255 is probably the most common (and more efficient) data column length in MySQL / MariaDB. Bytes are most certainly still relevant. MySQL will use 1 byte to store the length if it is less than 256, or more otherwise. Take a look at how C++ implements std::string if you think string lengths aren'...
ExpressJS How to structure an application?
...mplified here. Just keep it simple and stick a handful of .js files in the root of your repository and you're done. Voilà.
If your application is huge, at some point you need to break it up into distinct npm packages. In general the node.js approach seems to favor many small packages, at least for...
How do I get an apk file from an Android device?
...missions to access the directory your file is in. If not, you will need to root the device first.
If you find that many of the APKs are named "base.apk" you can also use this one line command to pull all the APKs off a phone you can access while renaming any "base.apk" names to the package name. ...
Rename multiple files in a directory in Python [duplicate]
...cter, set of characters or no character.
import os
paths = (os.path.join(root, filename)
for root, _, filenames in os.walk('C:\FolderName')
for filename in filenames)
for path in paths:
# the '#' in the example below will be replaced by the '-' in the filenames in the director...
Is there any performance gain in indexing a boolean field?
...e an index, if you have too many records it doesn't use the index anyways.
MySQL not using index when checking = 1 , but using it with = 0
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Installation Issue with matplotlib Python [duplicate]
...assume you have installed the pip matplotlib, there is a directory in your root called ~/.matplotlib.
Create a file ~/.matplotlib/matplotlibrc there and add the following code: backend: TkAgg
From this link you can try different diagrams.
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