Storing linkages between tables

I'm building an app that works on two databases -- own_db and external_db.

own_db has tables entities and attributes开发者_如何学编程 for all tables and columns in external_db respectively.

external_db has tables which are linked to each other for example employee can have a department etc. This linkage can be through a third table called *external_db.link_employee_department*.

Now own_db needs to preserve this linkage information for later use.

How do I storing this information? I guess there can be n number of linkage tables in between.

Ideas?

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This sounds like a data integration / application integration requirement. You could consider using an integration / middleware platform. These usually have repositories that can manage exactly this kind of source to target mapping with lineage tracking, impact analysis, versioning, etc. Some examples are: Oracle Fusion, IBM InfoSphere, Informatica, Ab Initio.