This topic explains why a file-based approach becomes unworkable and how a relational database solves the problem. You will study entities, attributes, tuples and relationships, along with primary, candidate, secondary and foreign keys, and the referential integrity that links tables together. Entity-relationship diagrams are used to model a database before it is built. Normalisation is covered up to third normal form, working through the reasons each stage removes a particular kind of redundancy.
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