Inserting data into table (eg.1)

<?php
$server = 'localhost';
$username = 'root';
$password = ' ';
$db = 'TNW';
$conn = mysqli_connect($server, $username, $password, $db);
if($conn){
    $query = "INSERT INTO `username` VALUES(1, 'Thet', 'Naing', 'thet', 'password1'),
                                                                     (2, 'Michael', 'Win', 'win', 'password2'),
                                                                     (3, 'Mya', 'Mya', 'myamya', 'password3')";
                                           
    $query_run = mysqli_query($conn, $query);
    if($query_run){
        echo 'Successfully inserted data into table.';
    }else{
        echo 'Inserting error or Data already exits.';
    }
}else{
    echo 'Connecting to a database Error.';
}
?>