Untitled

<!Doctype HTML>
<html>

    <head>
        <title>Aufgabe 2</title>
        <meta charset="UTF-8">
        <link rel="stylesheet" type="text/css" href="index.css">
    </head>

    <body>
        <h1 style="text-decoration: underline">Mitarbeiter</h1>
        <form method="post" action="" id="list" name="list">
            <select name="list" id="list" size="15%" style="width: 40%;">
                <?php $c = new Main(); $c->Refresh(); ?>
            </select>
        </form>
        <br>
        <br>
        <form method="post" action="index.php">
            <a class="inputbox">ID:</a><br> <input type="number" name="id" id="id"><br>
            <a class="inputbox" name="forename">Forename:</a><br> <input type="text" name="forename" id="forename"><br>
            <a class="inputbox" name="name">Name:</a><br> <input type="text" name="name" id="name"><br>
            <a class="inputbox" name="city">City:</a><br> <input type="text" name="city" id="city"><br><br>
            <button type="submit" name="sent" id="sent" value="sent">Hinzufügen</button>
        </form>
    </body>

</html>

<?php

class Main
{
    public $servername = "localhost";
    public $username = "admin";
    public $password = "admin";
    public $dbname = "aufgabe02";

    public $edit = false;

    function Refresh()
    {
        $con = new mysqli($this->servername, $this->username, $this->password, $this->dbname);

        if(!$con)
        {
            die("Connection Problem: ". $con->connect_error);
        }

        $sql = "SELECT * FROM aufgabe02.employee";
        $result = $con->query($sql);
        if(!$result)
        {
            die("SQL Problem: ". $con->error);
        }

        if ($result->num_rows > 0)
        {
            while ($row = $result->fetch_assoc())
            {
                $option = $row["id"] . " " . $row["forename"] . " " . $row["name"] . " " . $row["city"];
                echo "<option>" . $option . "</option>";
            }
        }

        $con->close();
    }

    function AddUser($id, $forename, $name, $city)
    {
        $con = new mysqli($this->servername, $this->username, $this->password, $this->dbname);

        if(!$con)
        {
            die("Connection Problem: ". $con->connect_error);
        }

        $sql = "INSERT INTO aufgabe02.employee (id, forename, name, city) VALUES ('".$id."', '".$forename."', '".$name."', '".$city."')";

        if (!$con->query($sql) === TRUE)
        {
            echo "Error: " . $sql . "<br>" . $con->error;
        }

        $con->close();

        $this->edit = false;
    }
}

if(isset($_POST['sent']) && !empty($_POST["sent"]))
{
   $id = $_POST["id"];
   $forename = $_POST["forename"];
   $name = $_POST["name"];
   $city = $_POST["city"];

   if(preg_match("/^[1-9]+$/", $id) && preg_match("/^[a-zA-Z]+$/", $forename) && preg_match("/^[a-zA-Z]+$/", $name) && preg_match("/^[a-zA-Z]+$/", $city))
   {
       $t = new Main();

       if($t->edit)
       {
           $t->AddUser("edit", "edit", "edit", "edit");
       }
       else
       {
           $t->AddUser($id, $forename, $name, $city);
       }
   }

}


?>