OOPHP MySQLi参数化查询不起作用？

Question

I have been trying to make this work for a couple of days now. I am wanting to evolve my knowledge of PHP and database security and am looking to use OOPHP and paramterized queries. I figured I would start off by simply connecting to the database and performing a select and displaying the results. I know the paramaterized query works on its own, but when I put it inside a class and call it, it won't grab the results and display them. Here is my code I've been working on:

<?php

class connect
    {
    public static function run()
        {
        $mysqli = new mysqli("*****", "*****", "*****");

        $db = "sales";
        mysqli_select_db($db);

        if(!$mysqli)
            {
            printf("Connection Failed: %s
", mysqli_connect_error());
            }
            else
                {
                echo("MariaDB Connection Successfull!!!");
                }
        }
    }

//call_user_func(array($className, 'run'));

class contacts
    {
    public function select()
        {
        if($stmt = $mysqli->prepare("SELECT CON_ID, CON_FNAME, CON_LNAME, CON_EMAIL FROM contacts"))
            {
            $stmt->execute();
            $stmt->bind_result($id,$fname,$lname,$email);

            echo("<table align='center' width='40%'");
            echo("<tr>");
            echo("<td align='center' width='25%'>Contact ID</td>");
            echo("<td align='center' width='25%'>First Name</td>");
            echo("<td align='center' width='25%'>Last Name</td>");
            echo("<td align='center' width='25%'>Email Address</td>");
            echo("</tr>");

            while($stmt->fetch())
                {
                echo("<tr>");
                echo("<td align='center' width='25%'>");
                printf("%s",$this->$id);
                echo("</td>");
                echo("<td align='center' width='25%'>");
                printf("%s",$this->$fname);
                echo("</td>");
                echo("<td align='center' width='25%'>");
                printf("%s",$this->$lname);
                echo("</td>");
                echo("<td align='center' width='25%'>");
                printf("%s",$this->$email);
                echo("</td>");
                echo("</tr>");
                }
            printf("</table>");
            $stmt->close();
            }
            else
                {
                printf("Prepared Statement Error: %s
", $mysqli->error());
                }
        }
    }

$connect = "connect";
$connect::run();
$contact = "contacts";
$contact::select();
?>

When I run the page, the only output I receive is "MariaDB Connection Successful!!!", but it doesn't seem to run the select() within the class "contacts". I am looking to learn better ways of coding with PHP, so if there is a better way, I would love to learn it!

I would be very grateful for any help that anyone can give.

Answer 1

There are 2 major problems with your code

1. You are using mysqli instead of PDO, making your goal ten times harder to reach
2. You are trying to do all at once. It is not way to go. Try to make yourself familiar with API, run some queries using just plain text code. Then combine these code into functions. And only then start for the class.