Database Concepts - Important Questions for Class 12
Chapter 11 - Database Concepts
This page contains important questions on Database concepts for Class 12 Computer Science. The questions cover definition of database, its need, advantages of database, data model and its types, concept of key, types of keys and relational algebra. These questions are useful for AHSEC/ASSEB Class 12 exam preparation
1. What is a database?
Answer :A database is an organized collection of related data that can be easily stored, accessed, managed and updated.
2. Why Do We Need a Database?
Answer :A database is required to store a large amount of data permanently is an organized manner. It enables us to insert, delete , update and find data easily in a database.
3. What are the advantages of a database?
Answer: Some of the advantages of database are:
- Easy access to data
Required information can be retrieved quickly.
- Reduces data redundancy
Unnecessary repetition of the same data can be reduced.
- Better data security
Access to sensitive information can be restricted to authorized users.
- Easy updating
Existing information can be changed without maintaining several separate copies.
- Data sharing
Multiple users can access the database according to their permissions.
- Better organization
Large amounts of information can be arranged systematically.
- Data consistency
Proper database design helps ensure that the same information does not have conflicting values in different places.
4. What is DBMS?
Answer :
DBMS stands for Database Management System.
A DBMS is software used to create, store, organize, retrieve, update and manage data in a database.
5. What is RDBMS?
Answer :RDBMS stands for Relational Database Management System. It is a software used to create and manipulate a relational database
6.What is a Data Model?
Answer : A data model is a collection of concepts used to describe the structure of a database, the relationships among data and the constraints on the data.
7. What are the three data models?
Answer :The 3 data models are:
- Relational data model
- Network data model
- Hierarchical data model
8.What is Relational Data model?
Answer :The relational data model represents data in the form of tables, also called relations.
Each table consists of:
- Rows
- Columns
9. What is network data model?
Answer : The network data model organizes data as a network of records connected through relationships.Unlike the hierarchical model, a record can have relationships with multiple other records.This allows more complex relationships.
10. What is hierarchical data model?
Answer :The hierarchical data model organizes data in the form of a tree-like structure.
It follows a parent-child relationship. A parent can have multiple children, but each child generally has only one parent.
11. What is a relation?
Answer :A relation is a table consisting of rows and columns.
12.What is an attribute?
Answer :An attribute is a column of a relation that represents a particular property of an entity.
13.What is a tuple?
Answer:A tuple is a row or record in a relation
14. What is a domain?
Answer : A domain is the set of permitted values that an attribute can have.
15. What is degree?
Answer : The degree of a relation is the number of attributes (columns) in the relation.
16. What is a cardinality?
Answer :The cardinality of a relation is the number of tuples (rows) in the relation
17. What is a key?
Answer : A key is an attribute or a group of attributes used to uniquely identify a record in a relation or to establish a relationship between tables.
18. What are the types of keys?
Answer : The types of keys:
- Primary key
- Candidate key
- Alternate key
- Foreign key
19. What is a primary key?
Answer : A primary key is an attribute or combination of attributes that uniquely identifies each tuple in a relation.
20. What is a candidate key?
Answer : A candidate key is an attribute or set of attributes that can uniquely identify each record and is eligible to become the primary key.
21. What is a alternate key?
Answer : An alternate key is a candidate key that is not selected as the primary key
22. What is a foreign key?
Answer : A foreign key is an attribute or set of attributes in one table that refers to the primary key of another table.
23. What is a relational algebra?
Answer :
Relational algebra is a procedural query language used to perform operations on relations (tables).
It provides a collection of operations that can be used to retrieve and manipulate data from relational databases.
24. What is a select operation?
Answer : The selection operation is used to select rows from a relation that satisfy a given condition.
25. What is a project operation?
Answer :The projection operation is used to select particular columns from a relation.
It is represented by: π (pi)