Relational vs E-R

What is wrong with E-R?

• Premature encapsulation of attributes within arbitrary entities. Forces the designer to make early commitments to data structures.
• Limited ability to model constraints which are intra-attribute, possibly intra-entity.
• Requires unmodeled methods to capture ad hoc procedural logic to express constraints.

What are some alternatives?

• Classic DFD > data dictionary > normalization > E-R per DeMarco or Gane & Sarson
• NIAM or Object Role Modeling
• OOAD??

Where to go from here:

• Conceptual, Logical, and Physical models
• The relational meta model
• CASE studies
• AIS Home
• Contact AIS at ddwelle@aisintl.com or feedback form