clasa conexion

<?php
class bd {
public $conexion;
public function conexion(){
    $this->conexion = new mysqli('localhost','root','','sagaz');

    if (mysqli_connect_error()) {
        die('Error de Conexión (' . mysqli_connect_errno() . ') '
                . mysqli_connect_error());
    }

    echo 'Éxito...';

    return $this->conexion;
}

public function consulta(){

    $query = ("select * from tabla");
$conexion2 = $this->conexion;
   $ejecutar = mysqli_query($conexion2,$query);

    if ($ejecutar != '0'){
echo "entro";

    }
    else {
        echo "no entro";
    }

}
}
$mostrarconexion = new bd();
$mostrarconexion->conexion();
$mostrarconexion->consulta();