I want to create a dropdown field filter. as in the attached file, if the dropdown 'select Regional' in the select to something, eg 'java'. then in the dropdown 'select province' will filter and display only province with regional java.
I'm guessing that you want something like the FilteredDropdownSet which you can read about [url=http://www.leftandmain.com/silverstripe-tutorials/2011/06/21/dropdown-drivel-two-new-form-fields-in-dom/]here[/url]. It's part of the DataObjectManager module so please download that and try it out.