Using an RDBMS database design, these problems are no longer a concern, because the tables and therefore their discrete data are associated with one another through relationships specified within the database. 

In the example, both the tables contain a column (or field) containing the person's name. 

In an RDBMS, these two tables could therefore be linked by the name field, or any other field they have in common.

Primary keys in an Employee table and a Department table.