<?php
    $host = "localhost";
    $user = "root";
    $pass = "";
    $dbname = "test";

    $conexao = mysqli_connect($host, $user, $pass);
    $db = mysql_select_db($conexao, $dbname);

    $nome = "exemplo";

    $consulta = mysql_query("SELECT * FROM usuarios_teste WHERE nome = $nome  ");
 ?>

$con = mysqli_connect("localhost", "my_user", "my_password", "my_db")