SSIS developer documentation is notoriously terse, and I’ve scoured Google looking for an answer on this…
What is the MappedColumnID property (available on input, output and external metadata columns) all about? It doesn’t appear to do anything useful.
Perhaps to rephrase the question… how do I achieve mappings between meta data columns and input / output columns? I know about the ExternalMetaDataColumnID property… but then how/where does MappedColumnID come into play?
Moreover, components like the OLEDB destination have a column mapping editor which appears in both the component UI as well as in the advanced editor. How is this achieved?
MappedColumnID is just an alternative way of identifying the columns instead of using there names.
From MSDN