Relational Database Design
Professor Program Version 3
Relationships in a Multiclass Program
Unrestricted Mulitplicity Relationship
Mulitplicity Relationship Based on Sections
Creating Relationships Between Data Tables
Establishing relationships enables the database program (e.g. Access) to enforce Referential Integrity:
Cannot add or modify records in referring tables to refer to non-existing records in a referred table.
Cannot delete a record from a referred table while other tables contain records that refer to it .
Steps to create a one-to-many relationship in Access:
1. Tools menu Relationships
2. Add all classes involved in the relationships. Professor and Course tables are primary tables,
Section table is a relational table (secondary table).
3. Drag foreign keys to primary keys they correspond to (Section' ProfId field to Professor ProfId field etc.)
4. Check Enforce Referential Integrity.
