Meu PHp

<?php

    class Database
{

    // specify your own database credentials
    private $host = "127.0.0.1";
    private $db_name = "sisim";
    private $username = "root";
    private $password = "";
    public $conn;

    // get the database connection
    public function getConnection()
    {

        $this->conn = null;

        try {
            $this->conn = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->db_name, $this->username, $this->password);
        } catch (PDOException $exception) {
            echo "Connection error: " . $exception->getMessage();
        }

        return $this->conn;
    }
}

*/


    class Empresa{

    //base de dados e nome da tabela

    private $conn;
    private $table_name = "cadastro_emp";

    //propriendades da Classe

    public $razao_social;
    public $cnpj;
    public $inscricao_estadual;


    public function __construct($db)
    {
        $this->conn = $db;
    }

    // create product
    public function create()
    {
        //write query
        $query = "INSERT INTO " . $this->table_name . " (`razao_social`,`cnpj`,`inscr_estadual`) VALUES (?,?,?)";
        echo($query);

        $stmt = $this->conn->prepare($query);

        $stmt->bindParam(1, $this->razao_social);
        $stmt->bindParam(2, $this->cnpj);
        $stmt->bindParam(3, $this->inscricao_estadual);

        if ($stmt->execute()) {
            return true;
        } else {
            return false;
        }

    }
}


    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
        $database = new Database();
        $empresa = new Empresa($database->getConnection());

        // set Empresa property values
        $empresa-> razao_social = $_POST['razaosocial'];
        $empresa-> cnpj = $_POST['cnpj'];
        $empresa-> inscricao_estadual = $_POST['inscricaoestadual'];

        // create the Empresa
    if ($empresa->create()) {
        echo "<div class=\"alert alert-success alert-dismissable\">";
        echo "<button type=\"button\" class=\"close\" data-dismiss=\"alert\" aria-hidden=\"true\">&times;</button>";
        echo "Empresa Cadastrada.";
        echo "</div>";
    } // if unable to create the Empresa, tell the user
    else {
        echo "<div class=\"alert alert-danger alert-dismissable\">";
        echo "<button type=\"button\" class=\"close\" data-dismiss=\"alert\" aria-hidden=\"true\">&times;</button>";
        echo "Erro ao Cadastrar.";
        echo "</div>";
    }
}
?>