If, for reasons of scaling and performance, you think that your DW database will, or may, reside on a different SQL instance from your OLTP database, you should also consider running the ETL using a tool such as SSIS. This allows you to decouple your databases (so that database A contains no references/dependencies to database B).
If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.