Clear textbox if checkbox unticked

I have a form that needs to be submitted and, if a checkbox is ticked an email textbox will appear where the visitor can enter their email address. If they change their mind an untick the checkbox, how can I get that untick action to empty the email text box?

The users have to agree to the website terms but the email address is only inserted into the database if they tick the email checkbox above. This works fine, but if they don't tick the box, I still need them to be taken to the next page. How can I achieve that please

You can do it server-side in php.

Just add a value attribute to your checkbox like value="1".

Then add code like this to the top of the page that processes the form:

<?php

if (!isset($_POST['c1'])) {

  $_POST['Email_Address'] = "";

}

?>

Thanks Ray - that worked although it still puts a NULL value in the database if it is unticked. Is there a way to get to the next page without putting a value in if the checkbox is unticked?

Also, is there a way to clear the email textbox if there is a value in there initially and then the user changes their mind and unticks the box. At the moment the value stays in there and is still inserted into the database even if they later untick the email check box?

Many thanks

Please attach a copy of the php page where the database is updated. I'll need to look at that to see what might be wrong with it.

Thanks please see attached

I don't see the code I told you to add on this page at all. It should be near the top somewhere above line 21.

Hi Ray

It's on line 170

....I have just moved it up

It has to be above the code that inserts into the database that starts on line 21 or it won't work.

I have just moved it up but still the same?

You mean the email address is still stored in the database when the checkbox is unchecked? I don't see how that would be possible with the code in place. Are you sure it was uploaded? I'd need FTP access to debug further, but it really appears that code would work.