ISYS114 Lecture Notes - Lecture 5: Associative Entity, Third Normal Form, Functional Dependency

• School: Macquarie University
• Department: Information Systems
• Course: ISYS114
• Professor: Charanya

Document Summary

1nf plus every non-key attribute is fully functionally dependent on the entire primary key. Every non-key attribute must be defined by the entire key, not by only part of the key. 2nf plus no transitive dependencies (functional dependencies on non-primary-key attributes) Note: this is called transitive, because the primary key is a determinant for another attribute, which in turn is a determinant for a third. Solution: non-key determinant with transitive dependencies go into a new table; non-key determinant becomes primary key in the new table and stays as foreign key in the old table. Purpose translate the logical description of data into the technical specifications for storing and retrieving data. Goal create a design for storing data that will provide adequate performance and ensure database integrity, security, and recoverability. Default value assumed value if no explicit value. Range control allowable value limitations (constraints or validation rules) Null value control allowing or prohibiting empty fields.