To copy a table from another database diagram
This action places the selected table definition on the Clipboard.
This diagram must be in the same database as the diagram that you are copying from.
The Clipboard contents appear at the new location and remain highlighted until you click elsewhere. If relationships exist between the selected tables and other tables in your diagram, relationship lines are automatically drawn.
When you edit the table in either diagram, your changes are reflected in both diagrams. Similarly, once you save the table in either diagram, the table is no longer considered “modified” in either diagram.
Copying a Table Across Database Diagrams