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Convert the ER diagram to relations in the normal manner to capture as many constraints as possible, and then identify which of the answers is a relation schema. A. Dependents(ID, name, bDate) B. Employees(ID, name, street, city, state, phones, sDate, lengthEmp) C. Coverage(ID, name) D. Employees(ID, name, street, city, state, sDate, lengthEmp)

Convert the ER diagram to relations in the normal manner to capture as many constraints as possible, and then identify which of the answers is a relation schema. A. Dependents(ID, name, bDate) B. Employees(ID, name, street, city, state, phones, sDate, lengthEmp) C. Coverage(ID, name) D. Employees(ID, name, street, city, state, sDate, lengthEmp)

Database System Concepts
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
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Convert the ER diagram to relations in the normal manner to capture as many constraints as possible, and then identify which of the answers is a relation schema. A. Dependents(ID, name, bDate) B. Employees(ID, name, street, city, state, phones, sDate, lengthEmp) C. Coverage(ID, name) D. Employees(ID, name, street, city, state, sDate, lengthEmp)
## Understanding Entity-Relationship (ER) Diagrams ### Overview ER diagrams are a visual tool used to model the relationships between different entities in a database system. This diagram focuses on the relationships between Employees and their Dependents in the context of coverage. ### Diagram Explanation #### Entities and Attributes 1. **Employees** - **Attributes**: - **ID**: Employee's unique identifier. - **name**: Employee's name. - **address**: Employee's address, which is further divided into: - **street**: Street portion of the address. - **city**: City portion of the address. - **state**: State portion of the address. - **phones**: Phone numbers of the employee. - **sDate**: Start date of employment. - **lengthEmp**: Length of employment. 2. **Dependents** - **Attributes**: - **name**: Dependent’s name. - **bDate**: Dependent's birth date. #### Relationships - **Coverages**: - This relationship signifies the coverage provided by an employee to their dependents. - **Cardinality**: - **1 on Employees side**: One employee can provide coverage. - **N on Dependents side**: One employee can cover many dependents. #### Diagram Components - **Rectangles**: Represent entities like Employees and Dependents. - **Ellipses**: Represent attributes of these entities. - **Diamond**: Represents relationships between entities. - **Lines**: Connect attributes to entities and entities to relationships. - **Cardinality Notations**: - "1": Indicates a single instance. - "N": Indicates many instances (N). ### Conclusion ER diagrams are essential for structuring data in relational databases. This specific diagram captures the relation of employees with their dependents through coverage, detailing the multiplicity and associated attributes clearly. Understanding this helps in designing efficient and logical database schemas.
Transcribed Image Text:## Understanding Entity-Relationship (ER) Diagrams ### Overview ER diagrams are a visual tool used to model the relationships between different entities in a database system. This diagram focuses on the relationships between Employees and their Dependents in the context of coverage. ### Diagram Explanation #### Entities and Attributes 1. **Employees** - **Attributes**: - **ID**: Employee's unique identifier. - **name**: Employee's name. - **address**: Employee's address, which is further divided into: - **street**: Street portion of the address. - **city**: City portion of the address. - **state**: State portion of the address. - **phones**: Phone numbers of the employee. - **sDate**: Start date of employment. - **lengthEmp**: Length of employment. 2. **Dependents** - **Attributes**: - **name**: Dependent’s name. - **bDate**: Dependent's birth date. #### Relationships - **Coverages**: - This relationship signifies the coverage provided by an employee to their dependents. - **Cardinality**: - **1 on Employees side**: One employee can provide coverage. - **N on Dependents side**: One employee can cover many dependents. #### Diagram Components - **Rectangles**: Represent entities like Employees and Dependents. - **Ellipses**: Represent attributes of these entities. - **Diamond**: Represents relationships between entities. - **Lines**: Connect attributes to entities and entities to relationships. - **Cardinality Notations**: - "1": Indicates a single instance. - "N": Indicates many instances (N). ### Conclusion ER diagrams are essential for structuring data in relational databases. This specific diagram captures the relation of employees with their dependents through coverage, detailing the multiplicity and associated attributes clearly. Understanding this helps in designing efficient and logical database schemas.
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