The paper describes a Computer Aided Software Engineering (CASE) tool to support conceptual database modelling. One popular approach for conceptual database modelling is use of the Entity-Relationship (ER) modeP. The paper proposes the use of an Enhanced Entity-Relationship (EER) model for conceptual database modelling. This Enhanced Entity-Relationship model extends the Entity-Relationship model by incorporating the generalization~specialization, aggregation and categorization abstractions. The CASE tool, which is based on the Enhanced Entity-Relationship model, is known as the Enhanced Entity-Relationship Diagrammer (EERD). In addition, the CASE tool supports direct visual query and update based on the EERM.
CASE tool, conceptual database modelling, enhanced-ER diagram
A data model is a group of concepts that help specify the structure of a database and a set of associated operations for specifying retrievals and updates on the database 2. Conceptual modelling is a high-level description of the structure of the database, independent of the particular choice of the hardware equipment and DBMS that will be used to implement the database.
The capability of the DBMS depends largely on the data model upon which the system is based. The importance of the data model as an interface to the database and as a backbone for the design of the query language cannot be over emphasized 3,4. Brodie 5 states that 'Data models are central to information systems .... Data models provide the conceptual basis for thinking about data-intensive applications and they provide a formal basis for tools and techniques used in developing and using information systems.' As such, many researchers consider the data model as the heart of the database management system.
The popular models for logical database modelling include the hierarchical, network and relational data models. The hierarchical model of data with its underlying tree-oriented data structures provides a direct and natural way to represent hierarchical organizations but has problems when used for situations with nonhierarchical relationships. The network model is based on ring-oriented data structures and has been used as a basis for implementing numerous commercial DBMSs.