php 如何使mysqli连接功能？
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How to make mysqli connect function?
提问by Jake Snake
I'm having a problem with a function that connects me to the database using mysqli. What I'm aiming to have is to just type getConnected();where I need the connection.
我有一个使用 mysqli 将我连接到数据库的函数的问题。我的目标是getConnected();在需要连接的地方输入。
This is the code:
这是代码：
function getConnected()
{
$host = 'localhost';
$user = 'logintest';
$pass = 'logintest';
$db = 'vibo';
$mysqli = new mysqli($host, $user, $pass, $db);
if ($mysqli->connect_error) {
die('Connect Error (' . mysqli_connect_errno() . ') '
. mysqli_connect_error());
}
}
This is the error I get when I try to use $mysqliafter calling getConnected():
这是我$mysqli在调用后尝试使用时遇到的错误getConnected()：
Notice: Undefined variable: mysqli in C:\xampp\htdocs\xampp\loginsystem\index.php on line 19
注意：未定义变量：mysqli in C:\xampp\htdocs\xampp\loginsystem\index.php 第 19 行
回答by Sam
As some users have suggested (and is the best way), return the mysqli instance
正如一些用户所建议的（也是最好的方法），返回 mysqli 实例
function getConnected($host,$user,$pass,$db) {
$mysqli = new mysqli($host, $user, $pass, $db);
if($mysqli->connect_error)
die('Connect Error (' . mysqli_connect_errno() . ') '. mysqli_connect_error());
return $mysqli;
}
Example:
例子：
$mysqli = getConnected('localhost','user','password','database');
回答by Dharman
You don't need to create such function. The connection to mysqli is only 3 lines of code when done properly. Definition and execution of such function would add twice as much.
您不需要创建这样的函数。如果正确完成，与 mysqli 的连接只需 3 行代码。此类功能的定义和执行将增加两倍。
Remember to always follow the three steps when opening a connection:
请记住在打开连接时始终遵循三个步骤：
- Enable mysqli error reporting.
- Create instance of mysqli class.
- Set the proper charset. Recommended one is
utf8mb4
- 启用 mysqli 错误报告。
- 创建 mysqli 类的实例。
- 设置正确的字符集。推荐一个是
utf8mb4
If you would like to have these 3 lines wrapped in a function you could do something like this:
如果您想将这 3 行包装在一个函数中，您可以执行以下操作：
function getConnected(): \mysqli {
$host = 'localhost';
$user = 'logintest';
$pass = 'logintest';
$db = 'vibo';
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli($host, $user, $pass, $db);
$mysqli->set_charset('utf8mb4');
// return the instance of mysqli class
return $mysqli;
}
However, hardcoding the values does not make much sense. The values should be coming either from environment variables (e.g. read using getenv()function) or from config file. For example:
但是，对值进行硬编码并没有多大意义。这些值应该来自环境变量（例如使用getenv()函数读取）或来自配置文件。例如：
function getConnected(): \mysqli {
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli(getenv('DB_HOST'), getenv('DB_USER'), getenv('DB_PASS'), getenv('DB_NAME'));
$mysqli->set_charset('utf8mb4');
// return the instance of mysqli class
return $mysqli;
}
