Table join inheritance
If you have common attributes across non-exclusive tables, you should consider normalizing your tables.  

It appears that Client, Employee, Manager, and Developer are all sub-types of the Person entity.  As such any attributes common to all types should be in the person entity, and attributes for the other entities should depend only on that sub-type.

I would expect Managers and Developers are often or always Employees.

Programmers while need to join the tables need to access the data required for their use case.  It may be appropriate to select from only from the subtype tables, or only from the Person table.