问删除textaera中的HTML标签(基本CMS)

EN

<?php include_once "includes/scripts.php"; ?>
<?php include_once "includes/connect.php";?>
<?php include_once "includes/cms_page_security.php";?>
<?php
    $sql = "SELECT * FROM content WHERE id = '5'";   
    $result = mysql_query($sql, $connect);
    $num= mysql_numrows($result);mysql_close();
    $row = mysql_fetch_row($result);
    $pg_content = $row['1'];
if (isset($_POST['saveChanges'])){
    $pgcontent = $_POST['edit'];
    $sql_query = ("UPDATE content SET cage_content= '$pgcontent' WHERE cage_content= '$pg_content'");
    mysql_query($sql_query,$connect);
    header('location: admin_cms_staff.php');
    $feedback = "Updated successfully";
    }
?>
<div id="cms_container"><br>
    <h1>Staff Page<img src="images/three_column_grid_line.png" alt="line"></h1>
      <form id="form1" name="form1" method="post">
         <textarea id="content" name="edit"><?php echo $pg_content; ?></textarea>
         <input type="submit" class="submit_edit" value="Save" name="saveChanges" onClick="alertFunction()">
     </form>
    <p class="logout_btn"><a href="admin_cms.php">Back</a></p>
     <?php if(isset($_POST['saveChanges'])){
        echo $feedback;}?>
    </div><!--cms_container-->
<script>
function alertFunction()
{
var r=confirm("Do you want to save the changes you made to the page?");
if (r==true)
  {
  }
else
  {
    return;
  }
}
</script>
</body>
</html>