Database Study Materials for Competitive Exams

Database

Advanced SQL Data and Database Administration Data Modeling with ER Model Data Models into Database Designs Data Warehousing Database Design Using Normalization Database Processing for BIS Database Redesign Distributed Databases ER Model and Business Rules Introduction to Database Introduction to SQL JDBC, Java Server Pages, and MySQL Logical Database Design Managing Databases with Oracle Managing Multiuser Databases Modeling Data in the Organization Object-Oriented Data Modeling Object-Oriented Database ODBC, OLE DB, ADO, and ASP Physical Database Design SQL for Database Construction SQL Server 2000 The Client-Server Database The Database Development Process The Database Environment The Internet Database Environment The Relational Model and Normalization XML and ADO.NET

Q. In a database, what does a 'foreign key' do?

A. Links two tables together
B. Identifies a unique record
C. Stores large amounts of data
D. Indexes a table for faster access

Solution

A foreign key links two tables together by referencing the primary key of another table.

Correct Answer: A — Links two tables together

Q. In a DBMS architecture, what does the term 'data independence' refer to?

A. The ability to change the data structure without affecting the application
B. The ability to access data from multiple sources
C. The ability to store data in different formats
D. The ability to secure data from unauthorized access

Solution

Data independence refers to the ability to change the data structure without affecting the applications that use the data.

Correct Answer: A — The ability to change the data structure without affecting the application

Q. In a distributed database, what is the purpose of data replication?

A. To ensure data consistency across all nodes
B. To reduce the size of the database
C. To increase the complexity of the system
D. To eliminate the need for backups

Solution

Data replication in a distributed database ensures data consistency across all nodes by maintaining copies of the same data in multiple locations.

Correct Answer: A — To ensure data consistency across all nodes

Q. In a multiuser database environment, what is a deadlock?

A. A situation where two transactions are waiting for each other to release locks
B. A method of data encryption
C. A type of database backup
D. A way to optimize queries

Solution

A deadlock occurs when two transactions are waiting for each other to release locks, preventing both from proceeding.

Correct Answer: A — A situation where two transactions are waiting for each other to release locks

Q. In a relational database, what does a foreign key represent?

A. A unique identifier for a table
B. A reference to a primary key in another table
C. An attribute of an entity
D. A constraint on data types

Solution

A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table.

Correct Answer: B — A reference to a primary key in another table

Q. In a relational database, what is a foreign key?

A. A unique identifier for a record
B. A key that links two tables together
C. A key that is not indexed
D. A key used for data encryption

Solution

A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table, establishing a link between them.

Correct Answer: B — A key that links two tables together

Q. In a relational database, what is the purpose of a foreign key?

A. To uniquely identify a record
B. To establish a relationship between two tables
C. To enforce data integrity
D. To improve query performance

Solution

A foreign key is used to establish a relationship between two tables, linking records in one table to records in another.

Correct Answer: B — To establish a relationship between two tables

Q. In a star schema, what do the fact tables contain?

A. Dimension attributes
B. Aggregated data
C. Transactional data
D. Metadata

Solution

Fact tables in a star schema contain transactional data that can be analyzed, often including measures and foreign keys to dimension tables.

Correct Answer: C — Transactional data

Q. In a star schema, what do the fact tables represent?

A. Dimensions of the data
B. Aggregated data
C. Transactional data
D. Metadata

Solution

Fact tables in a star schema represent transactional data, containing measurable, quantitative data for analysis.

Correct Answer: C — Transactional data

Q. In a star schema, what type of table is the central fact table surrounded by?

A. Dimension tables
B. Normalization tables
C. Transaction tables
D. Index tables

Solution

In a star schema, the central fact table is surrounded by dimension tables that provide context to the data.

Correct Answer: A — Dimension tables

Q. In an Entity-Relationship (ER) model, what does a diamond shape represent?

A. Entity
B. Attribute
C. Relationship
D. Weak entity

Solution

In an ER model, a diamond shape represents a relationship between entities.

Correct Answer: C — Relationship

Q. In an ER diagram, how is a multi-valued attribute represented?

A. As a rectangle
B. As an oval
C. As a double oval
D. As a diamond

Solution

A multi-valued attribute is represented as a double oval in an ER diagram.

Correct Answer: C — As a double oval

Q. In an ER diagram, what does a diamond shape represent?

A. Entity
B. Attribute
C. Relationship
D. Weak entity

Solution

In an ER diagram, a diamond shape represents a relationship between entities.

Correct Answer: C — Relationship

Q. In an ER model, how is a one-to-many relationship typically represented?

A. With a single line connecting two entities
B. With a crow's foot notation
C. With a dashed line
D. With a double line

Solution

A one-to-many relationship is typically represented with a crow's foot notation.

Correct Answer: B — With a crow's foot notation

Q. In an ER model, what does a circle represent?

A. An entity
B. An attribute
C. A relationship
D. A weak entity

Solution

A circle in an ER model represents an attribute of an entity.

Correct Answer: B — An attribute

Q. In an ER model, what does a diamond shape represent?

A. Entity
B. Attribute
C. Relationship
D. Weak Entity

Solution

In an ER model, a diamond shape represents a relationship between entities.

Correct Answer: C — Relationship

Q. In an ER model, what does an entity represent?

A. A relationship
B. A table
C. A column
D. A constraint

Solution

In an Entity-Relationship (ER) model, an entity represents a table in the database.

Correct Answer: B — A table

Q. In an ER model, what is an attribute?

A. A relationship between entities
B. A property or characteristic of an entity
C. A unique identifier for an entity
D. A type of database operation

Solution

An attribute is a property or characteristic that describes an entity in an ER model.

Correct Answer: B — A property or characteristic of an entity

Q. In DBMS architecture, what does the term 'physical data independence' refer to?

A. The ability to change the logical schema without changing the physical schema
B. The ability to change the physical storage without affecting the logical schema
C. The ability to access data from multiple sources
D. The ability to enforce security measures

Solution

Physical data independence refers to the ability to change the physical storage of data without affecting the logical schema.

Correct Answer: B — The ability to change the physical storage without affecting the logical schema

Q. In JDBC, which method is used to execute a SQL statement?

A. executeQuery()
B. runQuery()
C. executeSQL()
D. executeStatement()

Solution

In JDBC, the method used to execute a SQL statement is 'executeQuery()'.

Correct Answer: A — executeQuery()

Q. In SQL, which clause is used to filter records after grouping?

A. WHERE
B. HAVING
C. GROUP BY
D. ORDER BY

Solution

The HAVING clause is used to filter records after grouping in SQL.

Correct Answer: B — HAVING

Q. In the context of data warehousing, what does ETL stand for?

A. Extract, Transform, Load
B. Evaluate, Test, Launch
C. Execute, Transfer, Log
D. Extract, Transfer, Load

Solution

ETL stands for Extract, Transform, Load, which is the process of moving data from source systems into a data warehouse.

Correct Answer: A — Extract, Transform, Load

Q. In the context of DBMS architecture, what does 'three-tier architecture' refer to?

A. Data, Application, Presentation
B. Client, Server, Database
C. User, Application, Database
D. Data, Logic, User Interface

Solution

Three-tier architecture in DBMS refers to the separation of data, application logic, and presentation layers into three distinct tiers.

Correct Answer: A — Data, Application, Presentation

Q. In the context of distributed databases, what does the term 'partitioning' refer to?

A. Dividing data into smaller, manageable pieces
B. Combining multiple databases into one
C. Creating backups of the database
D. Encrypting sensitive data

Solution

Partitioning refers to dividing data into smaller, manageable pieces to improve performance and manageability in distributed databases.

Correct Answer: A — Dividing data into smaller, manageable pieces

Q. In the context of ER modeling, what does a 'weak entity' represent?

A. An entity that cannot exist without a strong entity
B. An entity with no attributes
C. An entity that has a composite key
D. An entity that is not related to any other entity

Solution

A weak entity represents an entity that cannot exist without a strong entity, relying on it for its identification.

Correct Answer: A — An entity that cannot exist without a strong entity

Q. In the context of ER modeling, what does an 'entity' represent?

A. A relationship between two tables
B. A unique identifier for a record
C. A real-world object or concept
D. A set of attributes

Solution

An 'entity' represents a real-world object or concept in ER modeling.

Correct Answer: C — A real-world object or concept

Q. What does a primary key do in an ER model?

A. Links two entities
B. Identifies a unique record
C. Defines a relationship type
D. Stores multiple values

Solution

A primary key uniquely identifies a record in a database table.

Correct Answer: B — Identifies a unique record

Q. What does a primary key in an ER model signify?

A. A unique identifier for an entity
B. A foreign key reference
C. An attribute that can be null
D. A relationship type

Solution

A primary key signifies a unique identifier for an entity in an ER model.

Correct Answer: A — A unique identifier for an entity

Q. What does an entity represent in an ER model?

A. A relationship between two tables
B. A real-world object or concept
C. A specific attribute of a table
D. A constraint on data

Solution

An entity represents a real-world object or concept in an ER model.

Correct Answer: B — A real-world object or concept

Q. What does concurrency control in a DBMS ensure?

A. Data redundancy
B. Data integrity during simultaneous access
C. Faster data retrieval
D. Data backup

Solution

Concurrency control ensures data integrity when multiple users access the database simultaneously.

Correct Answer: B — Data integrity during simultaneous access

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