PHP Update query not receiving variable already defined in page

Question

Hi I'm trying to update a single field from a HTML form, for some reason one of the session variables I am passing to the update query is not being accepted. I have already echoed the variable in the page so am fairly certain it exists in memory.

NB, I know my code is horrifically insecure but I'm learning PHP and once I've got the basics working Ill go over it and bring it upto best practice standards.

E2A: If I do var_dump($filename); before trying to run the query it returns string(6) "356/18", after the query it returns NULL. I'm not unsetting the variable anywhere so where could it be going!

Here is my form:

      <form method="post" action="">
      <p>Your username is:&nbsp;<?php echo $_SESSION['userid'] ?>&nbsp;Your company ID is:&nbsp;<?php echo $companyid['id']?></p>
      <h3>Please enter note for file: <?php echo $filename; ?></h3>
      <table width="200" cellpadding="5">
        <tr>
        <th width="18%" align="right" nowrap>Add Note:&nbsp;</th>
        <td width="82%" nowrap>
            <input type="text" name="note" />
        </td>
        </tr>
        <tr>
        <td colspan="2" width="100%" nowrap>
            <input type="submit" value="Submit" name="Submit" />
        </td>
        </tr>
        </table>
      </form>

Here is my UPDATE query:

     $sql = "UPDATE fields SET Notes =          ('".mysql_real_escape_string(stripslashes($_REQUEST['note']))."') 
        WHERE companyId='".$companyid['id']."' AND fileNumber ='".$filename."'";
    if($result = mysql_query($sql)) { 
        echo "<h1>Thank you</h1>Your information has been entered into our database<br><br>";
        echo $sql;
        echo $filename;
        } else { 
        echo "ERROR: ".mysql_error(); 
        } 
        } else { 

echoing $sql produces the following:

     UPDATE fields SET Notes = ('asdasda') WHERE companyId='11' AND fileNumber =''

and here is the bit where I instantiate the POST vars.

         include "header.php";
         $checkFiles = "checkFiles.php";
         // Catches form input from previous page and stores it into session variable called filename for future reference;
         $_SESSION['filename']=$_POST['filename'];
         $filename = $_SESSION['filename'];
         //User id stuff from previous page too; 
         $userid = $_SESSION['userid'];
         $id = mysql_query("SELECT id FROM users WHERE DXNumber='".$userid."'");
         // Returns pointer so fetch it as an array and insert it into variable $companyid for later use;
         $companyid = mysql_fetch_array($id);

Answer 1

You need to include session_start() on the top of each file.

Just do:

AND fileNumber ='".$_SESSION[filename]."'";

In your update query.

If that doesn't work, make sure that a value for $_SESSION[filename] is being set.

Answer 2

<h3>Please enter note for file: <?php echo $filename; ?></h3> 

Create a input box

<input type="text" name="filename" value="<?php echo $filename; ?>"/>

Then filename value will be pass to $_POST array