在PHP函数中启用db连接访问

我有一个简短的问题。我有一个检查密码是否有效的文件：

检查：

<?php
    include('inc/db.php');
    include('inc/functions.php');

    $myusername=$_POST['myusername']; 
    $mypassword=$_POST['mypassword']; 

    validateInput($myusername, $mypassword);
?>

功能：

<?php

        function validateInput($naam, $password) {

            $myusername = stripslashes($naam);
            $mypassword = stripslashes($password);
            $myusername = $conn->real_escape_string($myusername);
            $mypassword = $conn->real_escape_string($mypassword);

                    $sql = "SELECT * FROM user WHERE naam='$myusername' and paswoord='$mypassword'";

                    $result = $conn->query($sql);

                    if ($result->num_rows > 0) {
                      echo "ingelogd";

                    }else{
                        echo "niet ingelogd ";
                    }

       }
?>

---

您的问题可能很简单，但实际上非常广泛，有很多解决方案

示例不多：

好的一个单身汉
及

甚至更好的单体数据访问层
及

你可以在网上找到很多预制的DB类

谷歌的第一个结果-

坏的单球
及

一次错误-作为参数传递
$conn
（根据@LucM的建议）

（为什么不好？因为很可能您没有两个数据库，所以以这种方式编写代码是毫无意义的）

函数验证输入（$conn、$naam、$password）{
$myusername=stripslashes（$naam）；
$mypassword=stripslashes（$password）；
$myusername=$conn->real\u escape\u字符串（$myusername）；
$mypassword=$conn->real\u escape\u字符串（$mypassword）；
$sql=“从用户中选择*，其中naam='$myusername'和paswoord='$mypassword'；
$result=$conn->query（$sql）；
如果（$result->num_rows>0）{
回声“英格洛格”；
}否则{
呼应“尼特·英格洛德”；
}
}
$conn=newmysqli（$servername、$username、$password、$dbname）；
//检查连接
如果（$conn->connect\u错误）{
die（“连接失败：”.$conn->connect\U错误）；
} 
否则{
回声“作品

”；
}
..
验证输入（$conn、$naam、$password）；


另外值得一提的是，您不应该使用
stripslashes
和
real\u escape\u string
。PHP的mysqli模块支持，最好使用它们，而不是自己转义数据。
您必须在validateInput函数中定义$conn。您需要在
validateInput（）函数的范围内提供
$conn
。可能会添加
global$conn会有帮助。你也可以将连接作为参数传递。太棒了！一个简单的问题。在singleton示例中。我是否应该在get_instance函数中包含服务器名称和其他连接变量？@Merijndk这完全取决于您，您可以使用
$username=“…”创建单独的文件，如“db_config.php”；“$servername=“…”etc
并在连接之前包含它，因此
包含“db_config.php”；$conn=new static（$servername、$username、$password、$dbname）；
<?php
    $servername = "";
    $username = "";
    $password = "";
    $dbname = "";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 
    else{
        echo "works<br/><br/>";
    }

class db extends mysqli {

    static public function get_instance() {
        static $conn = null;
        if($conn == null) {
            $conn = new static($servername, $username, $password, $dbname);
        }
        return $conn;
    }
}

function validateInput($naam, $password) {

        $myusername = stripslashes($naam);
        $mypassword = stripslashes($password);
        $myusername = db::get_instance()->real_escape_string($myusername);
        $mypassword = db::get_instance()->real_escape_string($mypassword);

                $sql = "SELECT * FROM user WHERE naam='$myusername' and paswoord='$mypassword'";

                $result = db::get_instance()->query($sql);

                if ($result->num_rows > 0) {
                  echo "ingelogd";

                }else{
                    echo "niet ingelogd ";
                }

   }

class db {

    protected $conn;

    static public function get_instance() {
        static $obj = null;
        if($obj == null) {
            $obj = new static();
        }
        return $obj;
    }

    public function __construct() {
        $this->conn = new mysqli($servername, $username, $password, $dbname);
    }

    public function query($sql) {
        return $this->conn->query($sql);
    }

    public function escape($string) {
        return $this->conn->real_escape_string($string);
    }

    // this is good because you can handle errors etc, add insert/delete/update functions etc.

    public function insert($table_name, $fields) {
         // ..
    }

    public function update($table_name, $data, $where = null, $limit = null) {
         // ..
    }

    public function select($table_name, $where = null, $order_by = null, $limit = null) {
         // ..
    }

    // etc.

}

function validateInput($naam, $password) {
        ..
        $myusername = db::get_instance()->escape($myusername);
        $mypassword = db::get_instance()->escape($mypassword);
        ..
        $result = db::get_instance()->query($sql);
   }

function validateInput($naam, $password) {

        global $conn; // <-------- HERE

        $myusername = stripslashes($naam);
        $mypassword = stripslashes($password);
        $myusername = $conn->real_escape_string($myusername);
        $mypassword = $conn->real_escape_string($mypassword);

                $sql = "SELECT * FROM user WHERE naam='$myusername' and paswoord='$mypassword'";

                $result = $conn->query($sql);

                if ($result->num_rows > 0) {
                  echo "ingelogd";

                }else{
                    echo "niet ingelogd ";
                }

   }

$conn = new mysqli($servername, $username, $password, $dbname);
$GLOBALS['db'] = $conn;

function validateInput($naam, $password) {

        $myusername = stripslashes($naam);
        $mypassword = stripslashes($password);
        $myusername = $GLOBALS['db']->real_escape_string($myusername);
        $mypassword = $GLOBALS['db']->real_escape_string($mypassword);

                $sql = "SELECT * FROM user WHERE naam='$myusername' and paswoord='$mypassword'";

                $result = $GLOBALS['db']->query($sql);

                if ($result->num_rows > 0) {
                  echo "ingelogd";

                }else{
                    echo "niet ingelogd ";
                }

   }

function validateInput($conn, $naam, $password) {


        $myusername = stripslashes($naam);
        $mypassword = stripslashes($password);
        $myusername = $conn->real_escape_string($myusername);
        $mypassword = $conn->real_escape_string($mypassword);

                $sql = "SELECT * FROM user WHERE naam='$myusername' and paswoord='$mypassword'";

                $result = $conn->query($sql);

                if ($result->num_rows > 0) {
                  echo "ingelogd";

                }else{
                    echo "niet ingelogd ";
                }

   }


$conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 
    else{
        echo "works<br/><br/>";
    }

..

validateInput($conn, $naam, $password);