4.9

Page 1: Implementing Plural Attributes

• Initial Table

  • Implement plural attributes by relocating them to a new weak table.

• New Table Structure

  • Contains the plural attribute along with a foreign key referencing back to the initial table.

  • Primary key of the new table is a composite key that includes the plural attribute and the foreign key from the initial table.

  • The new table is closely associated with the initial table, indicating its dependence.

• Key Constraints

  • Primary key cascade rules and foreign key restrict rules must be defined for referential integrity.

• Naming Convention

  • The name of the new table is derived from the initial table name followed by the attribute name to denote its function clearly.

Page 2: Implementing Standard Attributes

• Attribute Types

  • Implement definition of standard attributes using teIee type for attribute specification.

  • The type specified for the attribute determines the exact data type for the corresponding column in the database.

Page 3: Implementing Foreign Key Requirements

• Foreign Key Constraints

  • Establish that if the table being referenced has a required entity, the corresponding column in the referencing table must also be marked as required (NOT NULL).

  • If the referencing table contains a singular entity, the foreign key column is defined as unique.

  • Ensuring data integrity includes setting specific constraints:

    • NOT NULL for required columns

    • UNIQUE specification for unique columns

    • PRIMARY KEY designation for primary key columns.

Page 4: Steps for Implementation

• Activities

  • 7A: Implement plural attributes by creating new weak tables.

  • 7B: Specify cascading and restricting rules for new foreign keys in these weak tables.

  • 7C: Define and specify column data types that correlate with the determined attribute types.

  • 7D: Enforce relationships and attribute cardinality using UNIQUE and NOT NULL constraints.