nav_admin_profile.php

<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<link rel="stylesheet" type="text/css" href="../admin/css/bootstrap.min.css" />
<!-- Navigation -->
<nav style="background-color:#3a223a;" class="navbar navbar-inverse navbar-fixed-top" role="navigation">
    <div class="container">


        <!-- Brand and toggle get grouped for better mobile display -->
        <div class="navbar-header">
            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1">
                <span class="sr-only">Toggle navigation</span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            <a class="navbar-brand" href="index.php"><img style="width: 140px;height: auto;position: relative;bottom:50%;left:8%;" src="header_img.png" /></a>
        </div>
        <!-- Collect the nav links, forms, and other content for toggling -->

        <div class="collapse navbar-collapse navbar-right" id="bs-example-navbar-collapse-1">
            <ul class="nav navbar-nav">

                <?php

                // $query = "SELECT * FROM cms_table";
                // $select_all_categories_query = mysqli_query($connection, $query);

                // while($row = mysqli_fetch_assoc($select_all_categories_query))
                // {
                //     $cat_title = $row['cat_title'];
                //     $cat_id = $row['cat_id'];

                //     echo "<li><a href='category.php?category=$cat_id''>{$cat_title}</a></li>";
                // }

                ?>


                <li>
                    <a href="admin">Admin</a>
                </li>
                <li>
                    <a href="#"><img style="width: 30px;height: 30px; cursor:pointer;" src="notification.png"/></a>
                </li>
                <li>
                    <a href="#"><img style="width: 30px;height: 30px; cursor:pointer;" src="messages.png"/> </a>
                </li>

                <!--                <li>-->
                <!--                    <a href="Registration.php">Register</a>-->
                <!--                </li>-->
                <!--                <li>-->
                <!--                    <a href="login.php">Login</a>-->
                <!--                </li>-->



                <li class="dropdown">
                    <a href="#" class="dropdown-toggle" data-toggle="dropdown"><img style="width: 30px;height: 30px; cursor:pointer;" src="user.png"/>
                        <?php
                        // PRINT username
                        if(!isset($_SESSION)) {
                            if(isset($_SESSION['username'])){
                                echo $_SESSION['username'];
                            }
                        }

                        ?>

                        <?php

                        // if(isset($_SESSION['username'])){
                        //     echo $_SESSION['username'];
                        // }

                        ?>

                        <b class="caret"></b></a>
                    <ul class="dropdown-menu">
                        <li>
                            <a href="profile.php"><i class="fa fa-fw fa-user"></i> Profile</a>
                        </li>
                        <li>
                            <a href="#"><i class="fa fa-fw fa-envelope"></i> Inbox</a>
                        </li>
                        <li>
                            <a href="settings.php"><i class="fa fa-fw fa-gear"></i> Settings</a>
                        </li>
                        <li class="divider"></li>
                        <li>
                            <a href="./includes/logout.php"><i class="fa fa-fw fa-power-off"></i> Log Out</a>
                        </li>
                    </ul>
                </li>


            </ul>
        </div>
        <!-- /.navbar-collapse -->
    </div>
    <!-- /.container -->
</nav>