Advance time from one list to another list

I have two lists/menus that are start and end times and I want to make the end time list/menu advance 2 hours from whatever is chosen in start list/menu. The values in both of the list/menu are

<select name="Time" class="Body" id="Time">
<option value="">Choose Start Time</option>
<option value="06:00:00">6:00 am</option>
<option value="06:30:00">6:30 am</option>
<option value="07:00:00">7:00 am</option>
<option value="07:30:00">7:30 am</option>
ETC........

<select name="Time2" class="Body" id="Time2">
<option value="">Choose End Time</option>
<option value="06:00:00">6:00 am</option>
<option value="06:30:00">6:30 am</option>
<option value="07:00:00">7:00 am</option>
<option value="07:30:00">7:30 am</option>
ETC........

any ideas on how to accomplish this? you can find my file at startend.php

----------------------------------------------------------------

I also tried this javascript but it doesn't add the additional 2 hours it just repeats the first value.

<script type="text/javascript">
function cfunc()
{
document.getElementById("Time2").value=document.getElementById("Time").value
}
</script>

<select name="Time" type="text" id="Time" onmouseup="cfunc()">
<option value="">Choose Start Time</option>
<option value="06:00:00">6:00 am</option>
<option value="06:30:00">6:30 am</option>
<option value="07:00:00">7:00 am</option>
<option value="07:30:00">7:30 am</option>
ETC..........

<select name="Time2" class="Body" id="Time2">
<option value="">Choose End Time</option>
<option value="06:00:00">6:00 am</option>
<option value="06:30:00">6:30 am</option>
<option value="07:00:00">7:00 am</option>
ETC...........

You can find this at 2fields.php

Thanks

if i understand you correctly, you may be able to achieve this using the dynamic dropdowns extension

You would need to hand code a javascript function that would loop through all of the items in the second list to rest their values based on the selection made in the first list.


This wont be supported by any of the available web assist extensions.

if you have dynamic dropdowns extension, you can use 2 recordsets to create a dynamic array, so that options for the second dropdown depend on the choice made in the first.

testdd.php

here, choosing 6.00 or 6.30 as the first option ensures that the second option contains only items at least 2 hours later, up to 4 hours later

choosing 7.00 as the first option reduces options in the second dropdown to 2-3 hours later