全局变量 - 数据库连接？ [英] Global Variable - database connection?

问题描述

我试图连接到一个数据库（MySQLi）只是一次，但是有这样的问题。

如何使连接全局的脚本？有多个文件（index.php，/classes/config.class.php，/classes/admin.class.php等）。

我试过以下内容：

In：config.class.php

  $ config = array（）; 
 public static $ sql; 
 
 function __construct（）{
 // database 
 db :: $ config ['host'] ='localhost'; 
 db :: $ config ['user'] ='_'; 
 db :: $ config ['pass'] ='_'; 
 db :: $ config ['db'] ='_'; 
 
 // connect 
 db :: $ sql = new mysqli（db :: $ config ['host']，db :: $ config ['user']，db :: $ config [pass']，db :: $ config ['db']）; 
} 
  

再次，在config.class.php

  public function contectToDatabase（$ sql）{
 $ sql = new mysqli（db :: $ config ['host']，db :: $ config ['user']，db :: $ config ['pass']，db :: $ config ['db']）; 
 $ this-> sql = $ sql; 
} 
  

我使用带有以下代码的类：
$ config = new db（）;

我真的很困惑我怎么做。任何人都可以帮忙？

---编辑---
这是我的新config.class.php文件：

  public static $ config = array（）; 
 public static $ sql; 
 
 private static $ db; 
 private $ connection; 
 
 public function __construct（）{
 // database 
 db :: $ config ['host'] ='_'; 
 db :: $ config ['user'] ='_'; 
 db :: $ config ['pass'] ='_'; 
 db :: $ config ['db'] ='_'; 
 // connect 
 $ this-> connection = new mysqli（db :: $ config ['host']，db :: $ config ['user']，db :: $ config [ pass']，db :: $ config ['db']）; 
} 
 function __destruct（）{
 $ this-> connection-> close（）; 
} 
 public static function getConnection（）{
 if（$ db == null）{
 $ db = new db（）; 
} 
 return $ db-> connection; 
} 
  

这是我如何加载它：

  require_once（classes / config.class.php）; 
 $ config = new db（）; 
 $ sql = db :: getConnection（）;但是，运行real_escape_string会导致以下错误：
 
 $ b 
 $ b 
 警告：mysqli :: real_escape_string（）[mysqli.real-escape-string]：无法在/home/calico/_/_.com/_中获取mysqli /index.php on line 20 
 
警告：mysqli :: query（）[mysqli.query]：无法在/home/calico/_/_.com/_/index中获取mysqli。 php on line 28 
  
 
 
解决方案
我个人使用单例类。像这样：
 <？php 
 
类数据库{
 
 private static $ db; 
 private $ connection; 
 
私有函数__construct（）{
 $ this-> connection = new MySQLi（/ * credentials * /）; 
} 
 
 function __destruct（）{
 $ this-> connection-> close（）; 
} 
 
 public static function getConnection（）{
 if（self :: $ db == null）{
 self :: $ db = new Database（） ; 
} 
 return self :: $ db-> connection; 
} 
} 
 
？> 
  
 
 
然后只需使用 $ db = Database :: getConnection（） code>无论我需要什么。
 
I am trying to connect to a database (MySQLi) just once, but am having problems doing so.

How do I make a connection global for the entire script? There are multiple files (index.php, /classes/config.class.php, /classes/admin.class.php, etc).

I've tried the following:

In: config.class.php
public static $config = array();
public static $sql;

function __construct() {
    // database
    db::$config['host'] = 'localhost';
    db::$config['user'] = '_';
    db::$config['pass'] = '_';
    db::$config['db'] = '_';

    // connect
    db::$sql = new mysqli(db::$config['host'], db::$config['user'], db::$config['pass'], db::$config['db']);
}
Again, in config.class.php
public function contectToDatabase($sql){
    $sql = new mysqli(db::$config['host'], db::$config['user'], db::$config['pass'], db::$config['db']);
    $this->sql = $sql;
}
I use the class with the following code:
$config = new db();

I really am puzzled at how I'm to do this. Can anyone help?

--- Edit ---
This is my new config.class.php file:
public static $config = array();
public static $sql;

private static $db;
private $connection;

public function __construct() {
    // database
    db::$config['host'] = '_';
    db::$config['user'] = '_';
    db::$config['pass'] = '_';
    db::$config['db'] = '_';
    // connect
    $this->connection = new mysqli(db::$config['host'], db::$config['user'], db::$config['pass'], db::$config['db']);
}
function __destruct() {
    $this->connection->close();
}
public static function getConnection() {
    if($db == null){
        $db = new db();
    }
    return $db->connection;
}
And this is how I'm loading it:
require_once("classes/config.class.php");
$config = new db();
$sql = db::getConnection();
However, running a real_escape_string results in the following errors:
Warning: mysqli::real_escape_string() [mysqli.real-escape-string]: Couldn't fetch mysqli in /home/calico/_/_.com/_/index.php on line 20

Warning: mysqli::query() [mysqli.query]: Couldn't fetch mysqli in /home/calico/_/_.com/_/index.php on line 28

解决方案
Personally, I use a singleton class.  Something like this:
<?php

class Database {

    private static $db;
    private $connection;

    private function __construct() {
        $this->connection = new MySQLi(/* credentials */);
    }

    function __destruct() {
        $this->connection->close();
    }

    public static function getConnection() {
        if (self::$db == null) {
            self::$db = new Database();
        }
        return self::$db->connection;
    }
}

?>
Then just use $db = Database::getConnection(); wherever I need it.

                        
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