PHP MySQL connection and select

mysql.php

<?php

    // Create connection
    $conn = new mysqli("localhost", "root", "");

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }
      

    echo "Connected successfully";

    mysqli_select_db($conn,"dbtest");
    $sql = "SELECT * from indovina_numero";

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

    $A= array();
    $B= array();
    $C= array();
    $D= array();
    $E= array();

    if ($result->num_rows > 0) {
        // output data of each row

        $i=0;

        while($row = $result->fetch_assoc()) {

            echo "A: " . $row["A"]. " B: " . $row["B"]. " C:" . $row["C"]. " D: ".$row["D"]." E: ".$row["E"]."<br>";
            $i++;
        }
    } else {
        echo "0 results";
    }