How to change my child drop down value when parent changes

Question

I want to change my second drop values when first drop down value changes. How to do that? I use php query to give values to drop down. go to http://ksm.allalla.com in that you can see one search form. i want to do that in that form

Answer 1

You need to implement JavaScript code and have it to do something like:

<SELECT NAME="firstDropdown" ONCHANGE="dropdownChanged()">
 ...
</SELECT>

And have the function dropdownChanged do the repopulating (change its values) of the data of secondDropdown