c# if or logic comparison

Can someone explain the logic of the ifs with || in c# because at the moment all three ifs execute

     string bla = "0";
        if (bla != "0" || bla != "")
        {
           //
            Console.WriteLine();
        }
        if (bla != "0" | bla != "")
        {
            //
            Console.WriteLine();
        }
        if (bla == "0" || bla == "")
        {
            Console.WriteLine();
            //
        }