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Normalization (Chapter 2)

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)

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Normalization (Chapter 2)

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  1. Normalization(Chapter 2) Peter Rob and Elie SemaanDatabases: Design, Development,and DeploymentUsing Microsoft Access Second Edition

  2. 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

  3. 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

  4. Partial Dependency PROJ_CODE EMP_NUM PROJ_NAME HRS_WORKED Partial dependency • 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)

  5. 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

  6. 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)

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

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

  9. 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

  10. 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 PROD_CODE PROD_TITLE LINE_NUM LINE_UNITS Transitive dependency

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

  12. 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 PROD_CODE LINE_UNITS LINE_NUM

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

  14. 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

  15. The END

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