Object-relational Impedance Mismatch

The object-relational impedance mismatch is a set of conceptual and technical difficulties that are often encountered when a relational database management system (RDBMS) is being used by a program written in an object-oriented programming language or style; particularly when objects or class definitions are mapped in a straightforward way to database tables or relational schemata.

The term object-relational impedance mismatch is derived from the electrical engineering term impedance matching.

Read more about Object-relational Impedance Mismatch:  Solving Impedance Mismatch, Contention, Philosophical Differences