Access External Data - Part 1 The Table UDF
Many databases provide the ability for accessing external data via a mechanism via a SELECT query. Examples include Linked Tables in MS-Access and External Tables in Oracle. A similar capability will become available in Teradata 15, it will be known as Query Grid. However users of Teradata prior to 15 are out of luck.
Teradata has provided the foundation for accessing external data via a SELECT query ever since Table UDF's were added in or around Teradata 12. There is even reference in the UDF programmers manuals to just such a facility (but no actual code to show how to do it).
In this article, you can download a working facility I've called DbLink that you can setup and use to access data from external data sources without having to write your own UDF.