大约有 31,600 项符合查询结果（耗时：0.0349秒） [XML]
When to use Common Table Expression (CTE)
...
I use them to break up complex queries, especially complex joins and sub-queries. I find I'm using them more and more as 'pseudo-views' to help me get my head around the intent of the query.
My only complaint about them is they cannot be re-used. For example, I may have...
Make virtualenv inherit specific packages from your global site-packages
...ch will contain just some libraries (which i chose) of the base python installation.
4 Answers
...
.htaccess - how to force “www.” in a generic way?
...
This solution works only if you want all sub-domains forwarded to www.yourdomain.com. If you only want to force www, you should update the second line to be: RewriteCond %{HTTP_HOST} ^yourdomain.com [NC]
– Jared Pomranky
Ma...
How can I prevent SQL injection in PHP?
...is way it is impossible for an attacker to inject malicious SQL.
You basically have two options to achieve this:
Using PDO (for any supported database driver):
$stmt = $pdo->prepare('SELECT * FROM employees WHERE name = :name');
$stmt->execute([ 'name' => $name ]);
foreach ($stmt as $...
What’s the best way to check if a file exists in C++? (cross platform)
...his using standard c++ libs? Preferably without trying to open the file at all.
10 Answers
...
pip install mysql-python fails with EnvironmentError: mysql_config not found
...
It seems mysql_config is missing on your system or the installer could not find it.
Be sure mysql_config is really installed.
For example on Debian/Ubuntu you must install the package:
sudo apt-get install libmysqlclient-dev
Maybe the mysql_config is not in your path, it will be ...
Display filename before matching line
... If grep is supplied with multiple file names, it will automatically display the file names before the match, but it will leave the file name out in case of a single input file. By using /dev/null as an extra input file grep "thinks" it dealing with multiple files, but /dev/null is of cou...
Apache Spark: The number of cores vs. the number of executors
...
To hopefully make all of this a little more concrete, here’s a worked example of configuring a Spark app to use as much of the cluster as
possible: Imagine a cluster with six nodes running NodeManagers, each
equipped with 16 cores and 64GB o...
Git: add vs push vs commit
...the suggested way to commit is the combined git commit -a, but you can mentally add a git add to the change block to understand the flow.
Lastly, the reason why push is a separate command is because of git's philosophy. git is a distributed versioning system, and your local working directory is your...
Get Output From the logging Module in IPython Notebook
.... The functions debug(), info(), warning(), error() and
critical() will call basicConfig() automatically if no handlers are
defined for the root logger.
This function does nothing if the root logger already has handlers
configured for it.
It seems like ipython notebook call basicConfig ...