db_cli.php

<?php
$host = 'localhost';
$user = 'root';
$pass = '';

try
{
    $conn = mysqli_connect($host, $user, $pass, 'test');
}
catch (Exception $e)
{
    echo $e->getMessage();
}

if($conn)
{
    echo "Username: ";
    $get_user = fgets(STDIN);
    echo "Password: ";
    $get_pass = fgets(STDIN);
    echo "Email: ";
    $get_email = fgets(STDIN);

    $sql = "INSERT INTO users (`user_NAME`, `user_PASS`, `user_EMAIL`) VALUES ('{$get_user}', '{$get_pass}', '{$get_email}')";
    $sql = mysqli_query($conn, $sql) or die("Problem s bd: ".mysqli_errno($conn));
    if($sql) echo "Uspeshno dobavi nov potrebitel s ime: {$get_user}";
}