Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech II DATABASE MANAGEMENT SYSTEMS Previous Question Paper (July/August - 2021 - R16)
Answer any Five Questions. All Questions Carry Equal Marks.
Main
What is E-R Model? Draw an E-R Diagram for any Banking system.
Answer
The Entity-Relationship (E-R) Model is a high-level conceptual data model used to describe the data requirements of an information system in a visual format. It represents the real-world scenario as a set of entities, their attributes, and the relationships between them, serving as a blueprint for database design before physical implementation.
Key components include:
- Entities: Real-world objects (e.g., Customer, Account).
- Attributes: Properties of entities (e.g., CustomerID, Balance).
- Relationships: Associations between entities (e.g., Customer 'owns' Account).
For a banking system, the E-R diagram involves the following structure:
1. Entities: Customer (CustomerID, Name, Address), Account (AccountNumber, Balance, Type), and Branch (BranchID, BranchName, Location).
2. Relationships:
- Customer owns Account (Many-to-Many relationship).
- Account maintained_at Branch (Many-to-One relationship).
- Customer works_at Branch (One-to-Many relationship).
In the diagram representation: Rectangles represent entities, ellipses represent attributes (with primary keys underlined), and diamonds represent relationships connecting the entities. Cardinality constraints (1:1, 1:N, M:N) are marked on the edges connecting entities to relationships to define the business rules of the banking operations.
What is Trigger? How to implement Triggers in SQL?
Answer
A Trigger is a special type of stored procedure that automatically executes or fires when a specific event occurs in the database server. These events include DML operations (INSERT, UPDATE, DELETE) on a table or DDL operations (CREATE, ALTER, DROP) on the database schema.
Triggers are implemented using the CREATE TRIGGER statement. The basic syntax involves defining the trigger name, the timing (BEFORE or AFTER), the event (INSERT, UPDATE, or DELETE), the target table, and the action to be performed.
BEFORE|AFTER event_type
ON table_name
FOR EACH ROW
BEGIN
-- SQL statements to execute
END;
When a trigger is defined, the database engine automatically monitors the specified table. If the defined event occurs, the trigger logic is invoked, allowing for complex auditing, data validation, or maintaining referential integrity that standard constraints cannot handle.
What is the difference between tuple relation calculus and domain relation calculus?
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What is normalization? What are the conditions required for a relation to be in 3NF and BCNF. What is the difference between 3NF and BCNF explain with example.
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Describe the steps in crash recovery ARIES algorithm.
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What is indexing? Explain B+ index with example.
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Discuss the relationship between Extendible and Linear Hashing.
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Explain the following: i) Database Users ii) Database Administrator.
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Distinguish between super key, Candidate key, Primary Key for a relation with examples.
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Define the terms primary key foreign key, and check constraints. How are these expressed in SQL?
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What are the applications of DBMS?
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List all DDL and DML commands with suitable examples.
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