iframe select content of left fram as link and post it to right frame-Collection of common programming errors

I am not a php expert so maybe my question is trivial

I have a page links.php with two iframes (left and right).

left lists Link sections after a query from db, right should list all links from a section after section has been selected by click.

the result – section’s names [Section] is displayed in left frame and a number for each row [Sectionid] has been requested,to

If I perform for test

   echo $row['Sectionid'];
   echo $row['Section'];

I get correctly both values for each row and of course the name of the section [Section] displays correctly.

now I want to post the request to right frame, where I need $Sectionid; for the query in the link table.

First I did the following:

  echo'' ;
  echo ''.$row['Section'].'';
  echo ""; 
  echo '';

This will show the content in the right frame as desired, but it displays a button with the section number in the left frame. Not exactly what I want. I would like to display the Section list on the left as links on the menu names to be selected. So I tried the following;

While in this case the section names are indeed displayed as links, when I click on one of these links it does not behave as desired.

First I get an answer in the same frame (the one that lists the Sections), so target is ignored

Second the value for Sectionid is not posted to linkcontent.php, as I get the errormessage:

Notice: Undefined index: Sectionid in /usr/share...

Simply it does not work.

How can I make perform php the action in order to obtain the result in the second frame as with the form command?

A minor question: when I first call link.php both frames listmenu.php and linkcontent.php of course are displayed, but right frame displays

Notice: Undefined index: Sectionid in /usr/share... 

as it did not receive any value, of course. While it is obvious that it cannot receive any value before a Section has been selected, I would like to suppress this message with some function telling not to expect a value for Sessionid if value for Sessionid is empty in order to have the page blank before any selection in the menu list.

Originally posted 2013-11-19 13:18:27.