Source mappings bind the entities in a diagram to their actual data. They define the relation between entities and attributes in a diagram with tables and columns in a database. This enables the generation of queries as well as producing a dependency graph. Source mappings are automatically maintained when for instance a new entity is being created by dragging in an existing table. In this way it is always possible to trace the origin of an entity. However, new source mappings can be added by dragging tables and columns onto entities and attributes.
There are several ways you can add source mappings:

1. You can add source mappings via the entity Properties window in the Source mappings tab, which is described below.The Source mappings tab provides a graphical representation of the mapped columns between the source entity and the target entity. The columns from the source entity that exists in the target entity are automatically mapped.
2. You can add source mappings in the diagram using a wizard, refer to Adding Source Mappings for details.
3. You can add source mappings in the diagram using drag and drop, refer to Dragging Tables to Add Source Mappings for details.