Systems Analysis and Synthesis

4.3. Entity-relationship Analysis

The process of making an object out of a relation, discussed in Section  4.2.4 to deal with many-to-many relations, is called reification. Reification is the basis of a design methodology called entity-relationship analysis. E-R analysis uses a bi-partite graph called an E-R diagram (or entity-relationship diagram ).

In the E-R diagram of Figure 4.3, the rectangles represent entities, and the rounded rectangles represent relationships between entities.¹⁷

FIGURE 4.3 An E-R diagram describing the Academic Records database. The Admitted To relation is reified as Admissions, Enrolled In as Enrolments, and Comprises