Answer: To represent a weak entity in a table, create a primary key with partial key attributes, establish a foreign key, and ensure total participation.
A weak entity is represented by a double rectangle in ER diagram in the DBMS. Follow the methods to represent weak entities in a table.
- Create a Primary Key: Begin by establishing a primary key for the weak entity. This should consist of its partial key attributes along with a discriminator.
- Identifying Relationship: Implement a strong identifying relationship with the related entity, ensuring that the weak entity’s identity is reliant on the related entity.
- Partial Key Attributes: Include the partial key attributes in the table, forming part of the primary key. These attributes alone are insufficient for unique identification.
- Foreign Key: Introduce a foreign key that references the related entity’s primary key. This establishes the connection between the weak entity and the entity on which it depends.
- Total Participation: Ensure total participation of the weak entity in the identifying relationship, indicating that each instance of the related entity corresponds to an instance of the weak entity.
- Include Additional Attributes: Add any additional attributes specific to the weak entity in the table, completing its representation.