I have a lookup field "Customer" in a list (Sales) from Customers List. I have a workflow on the Sales list. I need to get the ID from the lookup field. Is there a way to do that with workflow?
In workflow you can query data from another list. In your case Customer.
For detailed walkthrough please refer http://www.sharepointassist.com/2009/05/09/handling-lookup-columns-in-a-sharepoint-designer-workflow/