A Union Table is a virtual table that retrieves data from one or more data tables which you define using [Schema Modeler (PC)][/Tools/SchemaModeler] or Server Explorer (Mac). The Union Table is comprised of Union Table Fields which you define as the fields you are interested in, Source Tables which are the data tables you are retrieving data from, and Source Table Fields which are the fields in the Source Table, these are then mapped to the Union Table Fields.
The Union Table is similar to the SQL UNION operator except that it allows duplicate values by default.
To create a Union Table you define the fields that you are interested in. Then you add the tables you wish to retrieve the data from which auto generates mappings between the Union Table Fields and the Source Table Fields which you should then adjust to best fit your needs.
The Union Table can then be accessed as if it was a normal Data Table, except that it will contain an additional field,
@SourceTable, which indicates which of the Source Tables the row came from.
The following articles show how to create a Union Table using both [Schema Modeler (PC)][/Tools/SchemaModeler] and Server Explorer (Mac), and then access it.