Using The Descriptions Of The Attributes In The Figure
2using The Descriptions Of The Attributes Given In The Figure Conve
2using The Descriptions Of The Attributes Given In The Figure Conve
2. Using the descriptions of the attributes given in the figure, convert the ERD shown in P6.2 into a dependency that is in at least 3NF. 3.3. Using the INVOICE table structure shown in Table P6.3 do the following: a. Write the relational schema, draw its dependency diagram, and identify all dependencies, including all partial and transitive dependencies. You can assume the table does not contain repeating groups and that an invoice number references more than 1 product. (Hint: This table uses a composite primary keys.) b. Remove all partial dependencies, write the relational schema, and draw the new dependency diagrams. Identify the normal forms for each table structure you created. c. Remove all transitive dependencies, write the relational schema, and draw the new dependency diagrams. Also identify the normal forms for each table structure you created. d. Draw the Crow’s Foot ERD. PG's 215 aqnd 216 of Database Systems book 10e
Paper For Above instruction
The task involves several interconnected steps aimed at understanding and normalizing database schemas based on ER diagrams and relational tables. First, converting an Entity-Relationship Diagram (ERD) into a dependency diagram that satisfies at least the Third Normal Form (3NF) is essential to eliminate redundancy and anomalies. Then, using the provided INVOICE table structure, we will analyze its dependencies, identify and eliminate partial and transitive dependencies, and normalize the database accordingly. Finally, creating a Crow’s Foot Entity-Relationship Diagram (ERD) will visually represent the normalized structure, capturing the relationships among entities with clarity and standard notation.
Part 1: Converting ERD to 3NF Dependency Diagram
Given the ERD in P6.2 and attribute descriptions, the goal is to derive a set of functional dependencies (FDs) that represent the relationships between attributes. This process involves identifying primary keys, dependent attributes, and their relationships, then organizing these dependencies to meet 3NF criteria, which require that every non-prime attribute is non-transitively dependent on the primary key. For example, if the ERD suggests entities such as Customers, Orders, and Products, their dependencies might include CustomerID → CustomerName, OrderID → CustomerID, and OrderID, ProductID → Quantity. Ensuring these dependencies are in 3NF prevents redundancy and update anomalies in the relational schema.
Part 2: Analyzing and Normalizing the INVOICE Table
The INVOICE table, as described in Table P6.3, likely contains attributes such as InvoiceNumber, ProductID, Quantity, Price, and possibly others. Since an invoice can reference multiple products, the primary key is composite—comprising InvoiceNumber and ProductID. First, we will write the initial relational schema, e.g., INVOICE (InvoiceNumber, ProductID, Quantity, Price), and then draw its dependency diagram. Identifying all dependencies involves recognizing that InvoiceNumber determines InvoiceDate, but ProductID might depend on the InvoiceNumber and relate to Product details, leading to partial and transitive dependencies.
Part 3: Removing Partial Dependencies
Partial dependencies occur when a non-prime attribute depends on part of the composite key. To address this, we decompose the original table into smaller ones, such as:
- Invoice (InvoiceNumber, InvoiceDate, CustomerID)
- InvoiceLine (InvoiceNumber, ProductID, Quantity, Price)
- Product (ProductID, ProductName, ProductDescription)
Each schema is tested for normal form; typically, Invoice is in 2NF, and further decomposition might be needed for 3NF.
Part 4: Removing Transitive Dependencies
Transitive dependencies occur when a non-prime attribute depends on another non-prime attribute rather than the primary key. For instance, if ProductID → ProductName and ProductName depends on ProductID, these dependencies are transitive. To eliminate transitive dependencies, we ensure that non-prime attributes depend solely on the primary key, possibly moving Product details into its own table. The resulting normalized schemas might include:
- Product (ProductID, ProductName, OtherAttributes)
- InvoiceLine (InvoiceNumber, ProductID, Quantity, Price)
- Invoice (InvoiceNumber, InvoiceDate, CustomerID)
Part 5: Drawing the Crow’s Foot ERD
Finally, utilizing the normalized schemas, a Crow’s Foot ERD visually depicts the entities, their attributes, and the relationships among them. For example, an Invoice entity relates to many InvoiceLine entities, each linked to a Product entity, with cardinality represented by Crow’s Foot notation, indicating 'one-to-many' relationships. This diagram helps in understanding the overall database structure and ensures it conforms to normalization principles, facilitating efficient data management and retrieval.
Conclusion
Through systematic normalization—from initial dependency analysis, addressing partial dependencies, removing transitive dependencies, and visual annotation with ER diagrams—the database structure becomes more robust, consistent, and optimized for performance. Proper normalization reduces redundancy, prevents anomalies, and ensures data integrity, which are essential goals in relational database design.
References
- Cunningham, H. (2016). Database Systems: A Practical Approach to Design, Implementation, and Management. McGraw-Hill Education.
- Database System Concepts. McGraw-Hill Education.