Normalization (Chapter 2) Peter Rob and Elie Semaan Databases: Design, Development, and Deployment Using Microsoft Access Second Edition

Dependencies All key attributes must be dependent on the Primary Key (PK) If the PK is a composite PK and an attribute is dependent on only a part of the composite PK, a partial dependency exists If an attribute is dependent on a non-key attribute, it exhibits a transitive dependency

The Dependency Diagram EMP_NUM EMP_LNAME EMP_FNAME EMP_DOB PK is bold-faced and underlined (shown in orange) Single-attribute PK (simple PK) All employee attributes are dependent on the PK

Partial Dependency PROJ_CODE EMP_NUM PROJ_NAME HRS_WORKED PK components are bold-faced and underlined Multi-attribute PK (composite PK) All work assignment attributes are dependent on the PK But the PROJ_CODE, which is only a part of the PK, determines the PROJ_NAME (or the PROJ_NAME is dependent on the PROJ_CODE)

Transitive Dependency STU_NUM STU_LNAME DEPT_CODE DEPT_NAME Transitive dependency PK is bold-faced and underlined Single-attribute PK (simple PK) All student attributes are dependent on the PK But DEPT_CODE determines DEPT_NAME (or DEPT_NAME is dependent on DEPT_CODE, a non-key attribute

The First Normal Form (1NF) All key attributes are defined Each row/column intersection contains one and only one value, rather than a set of values All attributes are dependent on the primary key (PK)

Transitive dependency First Normal Form (1NF) INV_NUM LINE_NUM PROD_CODE PROD_TITLE CUS_NUM LINE_UNITS Transitive dependency Partial dependency

The Second Normal Form (2NF) Meets 1NF requirements Does not contain partial dependencies But does contain transitive dependencies

Normalization: Initial Decomposition 1. Identify each PK attribute in the 1NF dependency diagram. In this case, INV_NUM and LINE_NUM constituted the PK. INV_NUM 2. Write each PK attribute on a separate line LINE_NUM 3. Write the original PK on the final line INV_NUM LINE_NUM

Normalization: Creating New Structures INV_NUM CUS_NUM Table in 3NF; no partial or transitive dependencies LINE_NUM No dependencies, no table Table is in 2NF, with a remaining transitive dependency INV_NUM LINE_NUM PROD_CODE PROD_TITLE LINE_UNITS Transitive dependency

The Third Normal Form (3NF) Meets 2NF requirements Does not contain transitive dependencies

Normalization: Completed 3NF Structures Table name: INVOICE INV_NUM CUS_NUM 3NF; no partial or transitive dependencies Table name: PRODUCT PROD_CODE PROD_TITLE 3NF; no partial or transitive dependencies Table name: LINE 3NF; no partial or transitive dependencies INV_NUM LINE_NUM PROD_CODE LINE_UNITS

The Boyce-Codd Normal Form (BCNF) Meets 3NF requirements Every determinant in the table is a candidate key

Normalization: Boyce-Codd NF Panel 1 A B C D E F G 3NF, but not BCNF Panel 2 A E C D B F G Conversion to 2NF Partial dependency Panel 3 A E C D F G E B 3NF and BCNF

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