Solving the Problem by Taking Simple Projections - Teradata VantageCloud Lake

The problem with nulls in this table is resolved with a minor change in the logical design of the database. Because the attributes in this employee table are a combination of those that apply to all tuples and those that do not, the relationship is similar to that of a simple entity supertype and subtype, the difference being that the attribute in question, salary, is not unique: all employees receive a salary.

The following tables resolve the problem of multiple simultaneous semantics for the original employee table by taking projections from the original employee table: