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MySQL how to join tables on two fields
...'.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f498197%2fmysql-how-to-join-tables-on-two-fields%23new-answer', 'question_page');
}
);
Post as a guest
...
How to use glob() to find files recursively?
...ch against a simple expression:
import fnmatch
import os
matches = []
for root, dirnames, filenames in os.walk('src'):
for filename in fnmatch.filter(filenames, '*.c'):
matches.append(os.path.join(root, filename))
...
How does the SQL injection from the “Bobby Tables” XKCD comic work?
...ample, you can only run multiple statements in one SQL string by using the mysqli_multi_query function.
You can, however, manipulate an existing SQL statement via SQL injection without having to add a second statement. Let's say you have a login system which checks a username and a password with th...
JOIN queries vs multiple queries
... you are joining 3 or more tables on different keys, often databases (i.e. mysql) can only use one index per table, meaning maybe one of the joins will be fast (and use an index) whereas the others will be extremely slow. For multiple queries, you can optimize the indexes to use for each query.
...
Cannot change column used in a foreign key constraint
... DELETE ) will wait till timeout or UNLOCK TABLES; is executed
http://dev.mysql.com/doc/refman/5.5/en/lock-tables.html
EDIT 2: OP asked for a more detailed explanation of the line "The type and definition of foreign key field and reference must be equal. This means your foreign key disallows chang...
git: How to ignore all present untracked files?
...ead want to permanently ignore currently untracked files you can, from the root of your project, launch:
git status --porcelain | grep '^??' | cut -c4- >> .gitignore
Every subsequent call to git status will explicitly ignore those files.
UPDATE: the above command has a minor drawback: if y...
Very simple log4j2 XML configuration file using Console and File appender
... </File>
</Appenders>
<Loggers>
<Root level="debug">
<AppenderRef ref="Console" />
<AppenderRef ref="MyFile"/>
</Root>
</Loggers>
</Configuration>
Notes:
Put the following content in yo...
Ignore .pyc files in git repository
...in a .gitignore file in any of the directories leading from the repository root (inclusive).
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How to find the width of a div using vanilla JavaScript?
...{
const style = window.getComputedStyle(document.getElementById('__root__'));
if (style.height == 'auto') {
getStyleInfo();
}
// IF we got here we can do actual business logic staff
console.log(style.height, style.width);
}, 100);
};
window.on...
使用 JSON 和 Web API · App Inventor 2 中文网
...
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...