Normalization

• Is raw data in its original state.

  Unnormalized Data
• It might contain redundant data, multivalued data, and/or other data anomalies.

  Unnormalized Data
• Keywords (Unnormalized Data)

  Original State, Redundant Data, Multivalued Data
• Undesirable consequence of a data modification.

  Data Anomaly
• Keyword (Data Anomaly)

  Undesireable Consequence
• A process that assigns attributes to entities so that data redundancies are reduced or eliminated.

  Normalization
• Keywords (Normalization)

  Assigns attributes to entities, Data redundancies are reduced
• 5 Objectives of Normalization

  1. Each table/relation represents a single subject.
  2. Each row/column intersection contains only one value and not a group of values.
  3. No data item will be unnecessarily stored in more than one table.
  4. All nonprime attributes in a table are dependent on the primary key.
  5. Each table has no insertion, update, or deletion anomalies.
• Each rule in database normalization is called a normal form.
• 5 Most Common Normal Forms

  1. First Normal Form (1NF)
  2. Second Normal Form (2NF)
  3. Third Normal Form (3NF)
  4. Boyce Codd Normal Form (BCNF)
  5. Fourth Normal Form (4NF)
• There are no repeating groups and the primary key is identified.

  First normal form (1NF)
• 1NF and all the columns depend on the table’s primary key.

  Second normal form (2NF)
• 2NF and there are no non-key attributes determined by another nonkey attribute.

  Third normal form (3NF)
• Every determinant is a candidate key (special case of 3NF).

  Boyce-Codd normal form (BCNF)
• 3NF and no independent multivalued dependencies.

  Fourth normal form (4NF)
• Keywords (1NF)

  No repeating groups, Primary key is identified
• Keywords (2NF)

  Columns depend, Table’s primary key
• Keywords (3NF)

  Non non-key attributes, another non-key attributes
• Keywords (BCNF)

  Every determinant is a candidate key.
• Keywords (4NF)

  No independent multivalued dependencies
• First Objective of Normalization

  Each table/relation represents a single subject.
• Second Objective

  Each row/column intersection contains only one value and not a group of values.
• Third Objective

  No data item will be unnecessarily stored.
• Fourth Objective

  All nonprime attributes in a table are dependent on the primary key
• Fifth Objective

  Each table has no insertion, update, or deletion anomalies.