create Union query to concatenate results from multiple entities
The motivation for this enhancement came from both Kepler (wanting to merge data from like-structured datatables in an EMLDataSource actor) and from the FIRST project where a similar function is desired (but across many different packages).
Implementation is intended to be a straightforward SQL union/union all between two or more Query objects.
Updated by ben leinfelder about 16 years ago
created org.ecoinformatics.datamanager.database.UnionTest (test source tree)
modified org.ecoinformatics.datamanager.DataManager to execute Union queries (just like existing normal Query)