Informatics Practices Class 12 Important Questions Chapter 14 Back-End Database
1 Mark Questions
Question 1.
Write one point of difference between front-end and back-end with one example of each. (Delhi 2008)
Answer:
The front-end is an application, where user interacts directly with an application. The back-end provides an indirect support to the front-end, e.g. client/server.
Question 2.
What do you mean by a database system?
Answer:
A database management system consists of a collection of interrelated data and a collection of programs to access that data. The data describe one particular enterprise.
Question 3.
Explain the main purpose of database system.
Answer:
Database systems are designed to store large bodies of information. The management of data involves both the definition of structure for the storage of information and the provision of mechanism for the manipulation of information.
Question 4.
How does cost of system influence the selection of DBMS?
Answer:
The cost includes the purchase price, cost of operation, maintenance, site license, installation, data migration, data conversion.
Question 5.
Define a term storage manager.
Answer:
A storage manager is a program module that provides the interface between the low level data stored in the database and the application program and queries.
Question 6.
What is transaction manager?
Answer:
The transaction manager is responsible for ensuring that the database remains in a consistent state despite system failures. The transaction manager also ensures that concurrent transaction executions proceed without conflicting.
Question 7.
Give some examples of most commonly used database management systems.
Answer:
Most commonly used DBMSs include Oracle, IBM DB2, Microsoft SQL Server, Microsoft Access, PostgreSQL, MySQL and SQLite.
Question 8.
By whom the relational model was first time proposed?
Answer:
The relational model was first proposed in 1970 by Edgar F. Codd.
Question 9.
When does data loads into database in DDLC?
Answer:
After creation of the database, the data must be loaded into the database.
Question 10.
Name the first two phases of DDLC.
Answer:
The first two phases of DDLC:
- Requirement Analysis
- Conceptual Database Design
Question 11.
What is the last phase of DDLC?
Answer:
Maintenance
Question 12.
Why study of existing system is required in requirement analysis phase?
Answer:
Study of existing system is required because it is use to identify the data needs and requirements, the data volume, the performance requirements, the security issues, data access restriction, number and types of users, the growth rate of the database.
Question 13.
Which system is used to organise the database?
Answer:
DBMS is stands for Database Management System. It is used to organise the database. It is a collection of software for organising the information in a database.
2 Marks Questions
Question 14.
Describe the term back-end database.
Answer:
A back-end database is a database that is accessed by users indirectly through an external application rather than by application programming stored within the database itself or by low level manipulation of the data.
Question 15.
Write down the purpose of requirement analysis phase of database design?
Answer:
The requirement analysis is the first phase of Database Development Life Cycle (DDLC). At this stage, it is required to find out what is required? What kind of a database is needed for the organisation, what is the volume of the data that must be handled on a day-to-day basis (transaction data), how much data is to be stored in the master files and so on.
Question 16.
What do we do in the conceptual design stage?
Answer:
In the conceptual design stage, data modeling is used to create an abstract database structure that represents the real world scenario.
Question 17.
What is physical database design?
Answer:
In physical database design phase, we identify typical expected workloads that our database must support and further refinement of the database design so that it can meet the expected performance criteria.
Question 18.
Explain the significance of logical database design phase.
Answer:
In the logical design stage, the conceptual design is translated into internal model for the selected DBMS. This includes mapping all objects in the model to the specific constructs used by the selected database software.
Question 19.
What is the importance of schema refinement phase of DDLC?
Answer:
Schema refinement is important because in this phase we analyse the database design produced in logical design phase to identify the potential problems and refines it further.
Question 20.
Describe the Entity-Relationship model.
Answer:
In software engineering, an Entity-Relationship model (ER model for short) is an abstract way to describe a database. It usually starts with a relational database, which stores data in tables. Some of the data in these tables point to data in other tables.
Question 21.
Write some points about the relationship. Name different types of relationships of databases tables.
Answer:
Relationship states the way through which an entity is related with other entity.
There can be following types:
- One-to-one relationship
- One-to-many relationship
- Many-to-many relationship
Question 22.
What do you understand by one-to-one relationship?
Answer:
When one entity is related with one entity through a common attribute then such relation is known as a one-to-one relationship.
Question 23.
Explain any one relationship.
Answer:
When one entity is related with more than one entities through a common attribute or one attribute of an entity is related with more than one attributes of another table then such relation is known as a one-to-many relationship.
Question 24.
What do you understand by many-to-many relationship?
Answer:
When more than one attributes of one entity are related with more than one attributes of another table then such relation is known as a many-to-many relationship.
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