Display all students

<?php
    $db_host = '127.0.0.1';
    $db_user = 'root';
    $db_pass = 'root';
    $db_name = 'college';
    $conn = mysqli_connect($db_host, $db_user, $db_pass, $db_name);
    if($conn === false){
        die('Error while connecting:' . mysqli_connect_error());
    }
    $post = $_POST;
    $sql = "SELECT * FROM students";
    if($result = mysqli_query($link, $sql)){
        if(mysqli_num_rows($result) > 0){
            echo "<table>";
            echo "<tr>";
                echo "<th>ID</th>";
                echo "<th>First Name</th>";
                echo "<th>Last Name</th>";
                echo "<th>Email</th>";
            echo "</tr>";
            while($row = mysqli_fetch_array($result)){
                echo "<tr>";
                    echo "<td>" . $row['id'] . "</td>";
                    echo "<td>" . $row['first_name'] . "</td>";
                    echo "<td>" . $row['last_name'] . "</td>";
                    echo "<td>" . $row['email'] . "</td>";
                echo "</tr>";
            }
            echo "</table>";
            mysqli_free_result($result);
        } else {
            echo "Sorry! No records found.";
        }
    } else {
        echo "Error while executing $sql. " . mysqli_error($link);
    }

    // Close connection
    mysqli_close($link);

?>