XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 1 Level 3 Objectives: Identifying and Eliminating Database Anomalies by Normalizing Data Learn the techniques for normalizing data Evaluate fields that are used as keys Test the database design

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 2 Normalizing the Tables in the Database Normalization  Design process  Goals Reduces space required to store data by eliminating duplicate data in database Reduces inconsistent data in database by storing data only once Reduces chance of deletion update and insertion anomalies

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 3 Normalizing the Tables in the Database (continued) Deletion anomaly  User deletes data from database  Unintentionally deletes only occurrence of data in database Update anomaly  Due to redundant data in database  User fails to update some records or updates records erroneously Insertion anomaly  User cannot add data to database unless preceded by entry of other data

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 4 Normalizing the Tables in the Database (continued) Functional dependency  Column in table considered functionally dependent on another column If each value in second column associated with exactly one value in first column Partial dependency  Field dependent on only part of primary key Composite primary key  Primary key uses two or more fields to create unique records in table

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 5 Normalizing the Tables in the Database (continued) Determinant  Field or collection of fields whose value determines value in another field  Inverse of dependency Natural key  Primary key that details obvious and innate trait of record Artificial key  Field whose sole purpose is to create primary key  Usually visible to users

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 6 Normalizing the Tables in the Database (continued) Surrogate key  Computer-generated primary key  Usually invisible to users

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 7 First Normal Form Repeating group  Field contains more than one value First normal form  1NF  Does not contain any repeating groups

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 8 Second Normal Form 2NF Table must be in 1NF Must not contain any partial dependencies on composite primary key Tables in 1NF and contain primary key with only one field  Automatically in 2NF

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 9 Third Normal Form 3NF Only determinants must be candidate keys Candidate key  Field or collection of fields that could function as primary key but was not chosen to do so Transitive dependency  Occurs between two nonkey fields both dependent on third field Tables in 3NF should not have transitive dependencies

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 10 Level 3 Summary Normal forms  First (1NF)  Second (2NF)  Third (3NF)

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 11 Chapter Summary Discovery:  Identify existing and missing data  Organize data into tables  Determine data types for each field Table relationships  Established through common fields  Types 1:M 1:1 M:N

XP Chapter 1 Succeeding in Business with Microsoft Office Access 2003: A Problem-Solving Approach 12 Chapter Summary (continued) Normalization  Reduces duplication and inconsistency  Forms: 1NF 2NF 3NF