Evaluation of the E-R Model
Using data models to conceptualize the design of a database saves time and money because a completed E-R diagram is the actual blueprint of the database. Its composition must reflect an organization's operations accurately if the database is to meet that organization's data requirements.
The completed E-R diagram also lets the designer communicate more precisely with those who commissioned the database design. It’s easier to correct design flaws at the data modeling stage.
Do not confuse entities and relationships with actual tables. The transformation or decomposition of E-R models will be discussed within the next few weeks.
E-R modeling is an iterative process. Even when complete, ER models generally do not provide a complete picture (e.g., business rules cannot always be shown), therefore, much additional documentation is necessary.