Dynamic List of values

Hi,

I have requirement like...

Based on the 1st Level Input given to the Variable/Input Parameter, then the 2nd Variable should list out the values based on the first input selection.

Example...

We have a Customers and Sales Orders.

CustomerName     Domain

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

ABC                     Manufacturing

ABC                     Telecom

PQR                     Telecom

PQR                     Consulting

PQR                     Manufacturing

XYZ                      Telecom

XYZ                      Healthcare

XYZ                      Consumer

So 1st input is CustomerName and 2nd input is Domain.

Normally it displays Manufacturing, Telecom, Consulting, Healthcare, Consumer. for domain.

Suppose if I select

CustomerName as PQR

then the Domain should have list of values(selection display) only Telecom, Consulting, Manufacturing from which user will again select his respective filter.

Note: We are planning not to use SQL script.