CBSE/Karnataka PU Board PUC II CHAPTER 8 DATABASE CONCEPTS

50 MCQ (Multiple-Choice Questions) with Answers

Which component acts as an interface between database and users or application programs?
- a) Operating System
- b) DBMS
- c) Compiler
- d) Network
- Answer: b) DBMS
In a DBMS, what does 'DBMS' stand for?
- a) Data Bus Management System
- b) Database Manipulation Service
- c) Database Management System
- d) Data Base Monitoring Service
- Answer: c) Database Management System
Which of the following is an open-source DBMS?
- a) MySQL
- b) Oracle
- c) MS Access
- d) SQL Server
- Answer: a) MySQL
The snapshot of the database at a given time is called:
- a) Database Instance
- b) Database Schema
- c) Metadata
- d) Relation
- Answer: a) Database Instance
What is used to uniquely identify a tuple in a relation?
- a) Foreign Key
- b) Candidate Key
- c) Alternate Key
- d) Composite Key
- Answer: b) Candidate Key
The column in a table is also known as:
- a) Tuple
- b) Constraint
- c) Attribute
- d) Domain
- Answer: c) Attribute
Redundancy in a file system leads to:
- a) Easier data management
- b) Data inconsistency
- c) Faster access
- d) Secure data
- Answer: b) Data inconsistency
In a relational model, tables are referred to as:
- a) Sets
- b) Lists
- c) Relations
- d) Catalogs
- Answer: c) Relations
Primary Key is a:
- a) Candidate key chosen for unique identification
- b) Foreign key from another table
- c) Common key in all tables
- d) Composite key always
- Answer: a) Candidate key chosen for unique identification
If a guardian’s contact number is not available, what value should be used?
- a) Zero
- b) Default
- c) NULL
- d) Empty string
- Answer: c) NULL
Which constraint ensures an attribute must have a unique value?
- a) NOT NULL
- b) UNIQUE
- c) PRIMARY KEY
- d) DEFAULT
- Answer: b) UNIQUE
Who can update attendance data in a school database?
- a) Students
- b) Office Staff
- c) Teacher
- d) Anyone
- Answer: c) Teacher
Which operation refers to modifying database data?
- a) Deletion
- b) Update
- c) Insertion
- d) All of these
- Answer: d) All of these
DBMS catalog stores:
- a) Only schema
- b) Only data
- c) Metadata
- d) Constraints
- Answer: c) Metadata
Relation in a database means:
- a) Only one column
- b) Multiple tables
- c) A table with tuples and attributes
- d) No data entry
- Answer: c) A table with tuples and attributes
Alternate key in a relation is:
- a) Another name for primary key
- b) Candidate key not chosen as primary key
- c) Composite key
- d) None of these
- Answer: b) Candidate key not chosen as primary key
Foreign Key is used to:
- a) Identify tuples uniquely
- b) Relate two tables
- c) Store data
- d) Delete data
- Answer: b) Relate two tables
Composition of more than one attribute as a primary key is called:
- a) Alternate Key
- b) Composite Primary Key
- c) Unique Key
- d) Foreign Key
- Answer: b) Composite Primary Key
Which of the following is NOT a limitation of file system?
- a) Data Redundancy
- b) Data Isolation
- c) Controlled Sharing
- d) Data Encryption
- Answer: d) Data Encryption
Standard language for RDBMS is:
- a) Java
- b) HTML
- c) SQL
- d) Python
- Answer: c) SQL
Collection of logically related records is called:
- a) Catalog
- b) Relation
- c) File
- d) Schema
- Answer: c) File
Table storing guardian details should have:
- a) Only Name
- b) Name and Address
- c) GUID, Name, Phone, Address
- d) Only Phone
- Answer: c) GUID, Name, Phone, Address
A DBMS can be used to:
- a) Store Data
- b) Retrieve Data
- c) Modify Data
- d) All of these
- Answer: d) All of these
Data Constraints are used to:
- a) Restrict insertion of data
- b) Ensure data accuracy
- c) Format the database
- d) None of these
- Answer: b) Ensure data accuracy
What is the domain of an attribute?
- a) Maximum number of values
- b) Set of possible values
- c) Table relationship
- d) None
- Answer: b) Set of possible values
A relation having four fields is of:
- a) Degree 1
- b) Degree 2
- c) Degree 4
- d) Degree 3
- Answer: c) Degree 4
Data redundancy causes:
- a) Increased storage
- b) Consistent data
- c) Easier retrieval
- d) All of the above
- Answer: a) Increased storage
DBMS increases:
- a) Security complexity
- b) Data vulnerability
- c) Data sharing
- d) All of the above
- Answer: d) All of the above
A tuple means:
- a) Row in a table
- b) Column in a table
- c) Schema of database
- d) None of these
- Answer: a) Row in a table
In relational database, each attribute has:
- a) Unique name
- b) Multiple domains
- c) Computed key
- d) None of these
- Answer: a) Unique name
Cardinality in a relation is:
- a) Number of columns
- b) Number of rows
- c) Data value range
- d) Primary key
- Answer: b) Number of rows
Controlled data sharing allows:
- a) Every user to modify all data
- b) Only authorized users to modify data
- c) No data modification
- d) None of these
- Answer: b) Only authorized users to modify data
Data mapping is:
- a) Supported by file systems
- b) Not supported by file systems
- c) Not relevant
- d) Always automatic
- Answer: b) Not supported by file systems
Composite primary key is:
- a) A single field
- b) Two or more fields together
- c) Alternate key
- d) None of these
- Answer: b) Two or more fields together
Deletion operation does:
- a) Removes data from database
- b) Adds data
- c) Updates data
- d) None
- Answer: a) Removes data from database
A relation must have at least one attribute that is:
- a) NULL
- b) Unique and not NULL
- c) Repeated
- d) Alternative
- Answer: b) Unique and not NULL
DBMS provides:
- a) Data security
- b) Data consistency
- c) Data sharing
- d) All of these
- Answer: d) All of these
In ATM systems, database stores:
- a) Only user info
- b) Account, customer info
- c) Loan details
- d) All of the above
- Answer: d) All of the above
The attribute in attendance table to mark presence:
- a) AttendanceDate
- b) AttendanceStatus
- c) RollNumber
- d) SName
- Answer: b) AttendanceStatus
Degree of a table refers to:
- a) Rows
- b) Columns
- c) Relation
- d) None
- Answer: b) Columns
Which database model is discussed in the chapter?
- a) Document Model
- b) Relational Data Model
- c) Hierarchical Model
- d) Object-oriented Model
- Answer: b) Relational Data Model
A data dictionary is also called:
- a) Key Table
- b) Schema
- c) Metadata
- d) Relation Table
- Answer: c) Metadata
In DBMS, data can be:
- a) Inserted
- b) Deleted
- c) Modified
- d) All of the above
- Answer: d) All of the above
Which of the following is NOT a DBMS application?
- a) Banking
- b) Online shopping
- c) Text editing
- d) Inventory management
- Answer: c) Text editing
Which field connects STUDENT and GUARDIAN relations?
- a) SName
- b) RollNumber
- c) GUID
- d) GName
- Answer: c) GUID
What is NOT a property of a relation?
- a) Attributes have unique names
- b) Sequence of attributes is immaterial
- c) Tuples are ordered
- d) All values from same domain
- Answer: c) Tuples are ordered
A NULL value represents:
- a) Zero value
- b) Value not known or not applicable
- c) Minimum value
- d) Not allowed
- Answer: b) Value not known or not applicable
Structured Query Language is abbreviated as:
- a) SQL
- b) SQT
- c) SQU
- d) SGL
- Answer: a) SQL
Which of these is a limitation of DBMS?
- a) Increased complexity
- b) Data vulnerability
- c) Cost
- d) All of these
- Answer: d) All of these
Rows in a relation are called:
- a) Domains
- b) Tuples
- c) Degrees
- d) Attributes
- Answer: b) Tuples

20 Questions for Each Marks Category (with Answers)

1 MARK QUESTIONS

What is a DBMS?
- Answer: Database Management System, a software for managing databases.
Define primary key.
- Answer: An attribute that uniquely identifies each tuple in a relation.
What does SQL stand for?
- Answer: Structured Query Language.
Name one open-source DBMS.
- Answer: MySQL.
Define metadata.
- Answer: Data about the data, usually stored in the database catalog.
What is a tuple?
- Answer: A row in a table.
Define attribute in a relation.
- Answer: Column in a table.
What does degree of a relation mean?
- Answer: The number of attributes in a relation.
What is foreign key?
- Answer: An attribute that refers to the primary key of another relation.
What value is used when real data is unknown?
- Answer: NULL.
What is redundancy?
- Answer: Duplication of data.
Define cardinality of a relation.
- Answer: Number of tuples in a relation.
What is data constraint?
- Answer: Restriction on data to be inserted in a column.
Give one example of commercial DBMS.
- Answer: Oracle.
What is controlled data sharing?
- Answer: Limiting access to data based on user's role.
Define database schema.
- Answer: Design of the database structure.
Which language is standard for RDBMS?
- Answer: SQL.
What is a composite primary key?
- Answer: Primary key consisting of more than one attribute.
Define candidate key.
- Answer: Attribute(s) eligible to be chosen as primary key.
What does 'NULL' represent in databases?
- Answer: Unknown or non-existent value.

2 MARK QUESTIONS

Distinguish between database state and database schema.
- Answer: The database schema is the structure/design, while the database state is the data at a specific time.
Why are foreign keys allowed to have NULL values?
- Answer: To represent situations where a relationship does not exist or is not applicable.
What is redundancy and how can DBMS avoid it?
- Answer: Redundancy is duplicate data; DBMS avoids it by normalizing tables and using keys.
Compare composite key and alternate key.
- Answer: Composite key uses multiple attributes for uniqueness; alternate key is a candidate key not chosen as primary.
Why is data inconsistency a problem in file systems?
- Answer: It leads to unreliable and conflicting information.
Explain data manipulation in DBMS.
- Answer: Includes insertion, deletion, and updating of data.
What is a relational database?
- Answer: Database organized as tables (relations) with rows and columns.
Define metadata and give its use.
- Answer: Data about data, used to describe database schema and constraints.
Mention two limitations of file systems.
- Answer: Data redundancy and data isolation.
Explain domain in context of a relation.
- Answer: The set of allowed values for an attribute.
What is a query in DBMS?
- Answer: A request for data retrieval or manipulation.
Define degree and cardinality of a relation.
- Answer: Degree is no. of columns; cardinality is no. of rows.
List two benefits of DBMS over file systems.
- Answer: Minimized redundancy and efficient data management.
What are candidate keys?
- Answer: Attributes that may qualify as a primary key.
Explain data constraint with example.
- Answer: Constraint restricts values; e.g., UNIQUE forces unique values.
Give two examples of DBMS application.
- Answer: Banking and inventory management.
What is alternate key?
- Answer: Candidate key not used as primary key.
What does NOT NULL constraint imply?
- Answer: Attribute cannot have NULL value.
What is composite primary key?
- Answer: Combination of more than one attribute for unique identification.
State the use of foreign key.
- Answer: To relate two tables in a database.

3 MARK QUESTIONS

Explain the term 'Database Instance' with an example.
- Answer: The snapshot of the data at a specific moment; e.g., all student records loaded on October 15, 2025.
Describe limitations of file system and how DBMS overcomes them.
- Answer: File systems face redundancy, inconsistency, isolation, and no controlled sharing. DBMS merges data logically, allows controlled access, and eliminates redundancy.
Differentiate between primary and foreign keys.
- Answer: Primary key uniquely identifies rows within a table. Foreign key refers to primary key in another table, establishing a relationship.
What are the properties of relations in RDBMS?
- Answer: Attributes have unique names, tuple sequence is immaterial, and all values are atomic.
Define metadata. How is it useful?
- Answer: Metadata is 'data about data', like schema and constraints; used for database management and queries.
How does DBMS handle data manipulation?
- Answer: Through SQL queries that insert, delete, and update data.
Explain degree and cardinality with examples.
- Answer: Degree = no. of columns (attributes); Cardinality = no. of rows (tuples). E.g., Table with 4 columns and 5 rows has degree 4, cardinality 5.
State benefits of controlled data sharing in DBMS.
- Answer: Only authorized users can modify/view data, ensuring data security and privacy.
Describe keys and their types in a relational database.
- Answer: Candidate key, primary key, alternate key, composite key, and foreign key.
What are the uses of SQL in DBMS?
- Answer: SQL is used for querying, retrieving, inserting, updating, and deleting data.
What is a composite primary key? Give an example.
- Answer: Key formed by combining two or more attributes. E.g., RollNumber and AttendanceDate in ATTENDANCE table.
Why is redundancy undesirable in a database?
- Answer: Causes excess storage use and inconsistency in data.
Give two examples of real-life DBMS applications.
- Answer: Employee record management and online shopping.
Explain data constraint with a suitable example.
- Answer: E.g., mobile number must be 10 digits, enforced by a constraint.
How does DBMS overcome limitations of manual record keeping?
- Answer: Enables efficient data retrieval, modification, and sharing; eliminates manual errors.
Define a relation and its components.
- Answer: Relation = Table; components = attributes (columns), tuples (rows).
How does DBMS ensure data consistency?
- Answer: By centralizing data management, enforcing constraints and keys.
Explain the concept of schema and its importance.
- Answer: Schema defines the database structure; crucial for organization and management.
What is a NULL value? When is it used?
- Answer: Indicates unknown or inapplicable value; used when data is missing.
Differentiate between candidate key and alternate key.
- Answer: Candidate key is eligible to be primary; alternate key is candidate key not selected as primary.

5 MARK QUESTIONS

What are the limitations of file systems? Explain in detail how a relational DBMS overcomes these limitations.
- Answer: Limitations include redundancy, inconsistency, isolation, lack of controlled sharing. DBMS uses normalized tables with keys, centralizes data, ensures consistent updates, and allows secure access.
Explain with examples the concepts of primary key, foreign key, composite key, and alternate key in relational databases.
- Answer: Primary key uniquely identifies tuples (e.g., RollNumber in STUDENT). Foreign key refers to primary key in another table (e.g., GUID in STUDENT refers to GUARDIAN table). Composite key uses more than one attribute (e.g., RollNumber+AttendanceDate in ATTENDANCE). Alternate key is a candidate key not chosen as primary (e.g., GPhone in GUARDIAN).
Describe the properties of a relation and how they are implemented in a DBMS.
- Answer: Unique attribute names, distinct tuples, unordered sequence of tuples, atomic values, same domain for attribute values. Implemented by table design and constraints.
With reference to the school database example in the chapter, explain the design and schema of student, guardian, and attendance tables.
- Answer: STUDENT table stores roll number, name, date of birth, guardian ID. GUARDIAN table stores guardian ID, name, phone, address. ATTENDANCE table stores date, roll number, status. Keys relate tables for efficient management.
Justify the use of SQL as a standard language for RDBMS. Give examples of its statements.
- Answer: SQL enables structured queries for data manipulation and retrieval. Examples: SELECT * FROM STUDENT; INSERT INTO GUARDIAN VALUES (...); UPDATE ATTENDANCE SET Status='P' WHERE RollNumber=1.
Discuss the concept and use of metadata and data dictionary in DBMS.
- Answer: Metadata gives schema and constraints. Data dictionary stores metadata; used for data management, queries, and integrity enforcement.
Explain controlled data sharing and the levels of authorization possible in DBMS.
- Answer: Data access controlled by roles; teachers can update attendance, office staff can only view; parents view but not modify records. Implemented by access privileges.
Illustrate the need and use of constraints in database tables with suitable examples.
- Answer: Constraints enforce rules e.g., NOT NULL for mandatory fields, UNIQUE for identification, FOREIGN KEY to maintain relationships. Ensures data integrity and accuracy.
What do you understand by database schema and instance? Explain with examples.
- Answer: Schema defines structure (fields, types, constraints); instance is the current state of data. E.g., schema shows structure, instance is actual student records now.
Using canteen database example from the chapter, design tables and keys required for item storage and billing.
- Answer: Items table: ItemID, Name, Price, Calories. Billing table: BillID, ItemID (foreign key), Quantity. ItemID is primary key in Items; BillID is primary in Billing; ItemID in Billing refers to Items prime key.
Describe with example how DBMS helps in minimizing redundancy with relational design.
- Answer: Redundancy is minimized by keeping unique entries in related tables. E.g., guardian info stored once in GUARDIAN, referenced in STUDENT by GUID.
What are candidate keys? How does a DBMS use them to ensure data integrity?
- Answer: Candidate keys are fields eligible for primary key. DBMS uses chosen keys for unique identification, others as alternate keys.
Give a detailed comparison of file system and DBMS for data storage and management.
- Answer: File system is manual, prone to errors, data duplication, tough querying. DBMS offers computerized logical storage, quick queries, controlled sharing, and less redundancy.
In context of the given chapter, explain the data constraint types and their applications.
- Answer: NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, DEFAULT. Used for mandatory values, unique identification, linking tables, and default settings.
What are the security and vulnerability concerns in DBMS? How are they addressed?
- Answer: Centralized data risks entire system failure. Security managed with backups, access privileges, and hardware/software checks.
Explain the structure of a relational model in DBMS with diagrams (describe in words).
- Answer: Tables represent entities (rows as tuples, columns as attributes), linked by keys. E.g., STUDENT, GUARDIAN, and ATTENDANCE tables, linked by GUID and RollNumber.
Discuss data manipulation operations with SQL statements.
- Answer: Data can be inserted (INSERT), deleted (DELETE), updated (UPDATE), and selected (SELECT) using SQL, ensuring easy management and retrieval.
Describe the use of relational model in real-life applications such as banking or inventory management.
- Answer: Banking uses tables for customers, transactions, loans, all linked by keys. Inventory for items, orders, customers, each as a relation, ensuring efficient data flow and management.
How does DBMS ensure accuracy and reliability of data?
- Answer: By enforcing constraints, using keys for uniqueness, and controlling manipulation privileges, DBMS keeps data accurate and reliable.
Explain the concept of alternate key and provide suitable examples from chapter context.

Answer: Alternate key is a candidate key not chosen as primary. E.g., GUID is primary in GUARDIAN, GPhone is alternate key as it is also unique.

[NOTE: Kindly cross check answers once from other source also, Quantity and Quality of answers also kindly check before use, specially 5 marks answers are not sufficient kindly add from your side, this gives just quick review]

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