What is "der"

ER diagrams are used to model and create relational databases, in terms of logical and business rules (in a logical data model) and in terms of the specific technology to be implemented (in a physical data model.) In software engineering, an ER diagram is often an initial step in determining requirements for an information systems design. It is also used to model certain databases. A relational database has an equivalent relational table, and can potentially be expressed in this way as necessary.

ER diagrams are used to analyze existing databases to find and solve logic or implementation problems. When drawing the diagram, the error should be revealed.