Add transformations to external data tables (and database pushback of these)

Spotfire lacks one very important feature to make data preparation more useful: basic operations on external tables.

Other tools offer this in terms of joins, filters for row and columns, simple calculations, aggregation and similar. All these operations would be possible to be 'pushed back' into a single SQL query. This way, users can build a true data pipeline without executing queries on the way (might take a long time) and have only the complete pipeline being executed at once (this is probably fast enough as the query is already specific and the result set smaller). As the result should be small enough now, the resulting table would be possible to store internal and thus enable all analytics features that make Spotfire a great tool!