INFS1603 Lecture Notes - Lecture 8: Dependency Graph, First Normal Form, Unique Key

• School: UNSW, UNSW Sydney
• Department: Information Systems
• Course: INFS1603
• Professor: All

Document Summary

The first normal form (1nf) describes the tabular format in which: all of the key attributes are defined, or no multivalued attributes, there are no repeating groups on the table. In other words, each row/column intersection contains one and only one value, not a set of values: all attributes are dependent on the primary key. Repeating group: a group of multiple entries of the same type can exist for any single key attribute occurrence. Start by presenting the data in a tabular format where each cell has a single value and there are no repeating groups. To eliminate repeating groups, eliminate the nulls by making sure that each repeating group attribute contains an appropriate data value. However, (proj_num, emp_num) uniquely identifies all other attributes within the table. Since we have identified the pk, we have identified the following dependency: Proj_num, emp_num -> proj_name, emp_name, job_class chg_hour, hours (fully functional dependency) 1nf: all_in_one (proj_num, proj_name, emp_num, emp_name, job_class, chg_hour, hours)