When adding source columns to a table object in RED, the target table's current source columns are used to create the first source mapping object and then proceeds to create the second source mapping object which contains the additional source columns that need to be mapped to the target table. The columns from the source table that exists in the target table are automatically mapped.
The process of adding Source Mappings is initiated when a source table is dragged and dropped to an existing table object in RED.
The user is prompted with the following options:
- New Table - Opens a new dialog that enables you to create the dropped table as a new object in the metadata repository.
- Add Columns - Inserts the columns of the dropped table into the target table.
- Add Source Mapping - Inserts a new source mapping into the target table.
Note
If you are creating the first source mapping, the target table is first converted to a source mappable object, and then a new source mapping is inserted. If it is not the first source mapping, a new source mapping is just inserted into the target table.
The alternative method is to right click the target table from the Objects list pane and then select the Add Source Mapping option from the context menu: