Advanced Database · Unit 1 · 8 hrs
Enhanced Entity Relationship Model and Relational Model
Exam-focused notes for Enhanced Entity Relationship Model and Relational Model (Advanced Database, CSC475): what the TU syllabus asks and how it has actually been tested, with 8 solved past questions from this unit.
What this unit covers
- Entity Relationship Model Revised
- Subclasses, Superclasses and Inheritance
- Specialization and Generalization
- Constraints and characteristics of specialization and Generalization
- Union Types
- Aggregation
- Relational Model Revised
- Converting ER and EER Model to Relational Model
- SQL and Advanced Features
- Concepts of File Structures, Hashing, and Indexing
Constraints and characteristics of specialization and Generalization
Explain different constraints of specialization and generalization. [5]
Specialization and Generalization are key concepts in the Enhanced Entity-Relationship (EER) model. There are two main constraints that apply to both specialization and generalization: --- This constraint specifies whether every entity in the superclass mus...
Full solved answer →Design an EER model for library management system having generalization and specialization hierarchies. The EER model should have disjoint and overlapping constraints with at least one of the entities having total participation. Use your own assumption for other concepts. Now convert the EER diagram into its equivalent relational model.[10]
- A Person is the superclass with two subclasses: Member and Staff (Generalization hierarchy, Disjoint -- a person is either a member or staff, not both) - A LibraryItem is the superclass with subclasses: Book, Journal, and DVD (Specialization hierarchy, Ov...
Full solved answer →Concepts of File Structures, Hashing, and Indexing
What is hashing? How does hashing improve database efficiency? [5]
Hashing is a technique used to search the location of desired data on disk. It uses a mathematical function called a hash function to calculate the direct location (address) of a data record stored in data blocks (also called data buckets) on disk, without ...
Full solved answer →Why hashing is important to store data in databases? What is primary file organization? [5]
--- Hashing is a technique that allows searching for the location of desired data on disk. It uses a mathematical function called a hash function to calculate the storage location of data records. - In large databases, it is not possible to search all the i...
Full solved answer →Why indexing is important to store data in database? What's multilevel index? [5]
--- When executing SQL queries, it takes some amount of time to access data from the disk. An index is a data structure that helps to find and access data in a table of a database quickly. Indexing technique reduces the number of disk accesses required to p...
Full solved answer →Specialization and Generalization
Explain different features of enhanced ER(EER) model. Compare specialization with generalization.[10]
--- The traditional ER model is not sufficient for representing new, complex database applications such as: - Engineering design and manufacturing (CAD/CAM) - Telecommunications systems - Geographic Information Systems (GIS) To address these limitations, th...
Full solved answer →Aggregation
Explain aggregation with suitable example. [5]
Aggregation is a feature in the Enhanced Entity-Relationship (EER) model that allows a relationship set to participate in another relationship set. It is used when we need to express a relationship between a relationship and an entity, which cannot be repre...
Full solved answer →What is aggregation? Explain with example. [5]
Aggregation is an abstraction concept in the Entity-Relationship (ER) model where a relationship itself is treated as a higher-level entity. It is used when a relationship between entities needs to participate in another relationship. In other words, aggreg...
Full solved answer →Make Unit 1 stick
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