This is my LOCAL URL:

http://localhost/wbdrupal/?url=http://werkbad-konfigurator.de/datahub/searchObjectByID?table=furniture&column=wbid&search=

when I echo this variable $_GET['url'];

then the output is http://werkbad-konfigurator.de/datahub/searchObjectByID?table=furniture

but I need output as http://werkbad-konfigurator.de/datahub/searchObjectByID?table=furniture&column=wbid&search=

I need full query string when I write this command: echo $_GET['url'];

Your URL is malformed and can't be parsed. The system has no way of knowing which key/value pairs belong to the actual URL or to the url value you're trying to submit.

You need to URL-encode your values so the system can know what the key/value pairs are:

http://localhost/wbdrupal/?url=http%3A%2F%2Fwerkbad-konfigurator.de%2Fdatahub%2FsearchObjectByID%3Ftable%3Dfurniture%26column%3Dwbid%26search%3D