Database Concepts

CBSE Informatics Practices. File systems and their limits, DBMS, relations, tuples and attributes, degree and cardinality, candidate, primary, alternate and foreign keys, referential integrity. Every sheet has 20 questions in three sections and an answer key, and the questions change every time.

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Sample questions

Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.

Section A · multiple choice

1.
A DBMS is:
1. a kind of printer
2. an input device
3. a single text file
4. software to create, store, manage and query databases
Answer
(d) software to create, store, manage and query databases
2.
What is the degree of this relation? Relation: STUDENT AdmNo | RollNo | Name | Section | City 1012 | 27 | Ritu | B | Patna 1101 | 28 | Pooja | A | Kochi 1461 | 29 | Manav | A | Pune 1702 | 30 | Zoya | A | Patna 1835 | 31 | Rahul | A | Kochi 1913 | 32 | Zoya | B | Kochi
1. 4
2. 5
3. 6
4. 7
Answer
(b) 5
degree = number of attributes (columns)
3.
What is the cardinality of this relation? Relation: STUDENT AdmNo | RollNo | Name | Section | City 1120 | 29 | Kabir | B | Patna 1436 | 30 | Bhavna | A | Patna 1511 | 31 | Sana | B | Kochi 1519 | 32 | Pooja | B | Patna 1568 | 33 | Uday | B | Patna 1600 | 34 | Jaya | B | Agra 1822 | 35 | Sana | A | Pune 1889 | 36 | Meera | B | Pune
1. 5
2. 7
3. 9
4. 8
Answer
(d) 8
cardinality = number of tuples (rows)

Section B · short answer

4.
Give two limitations of a file system for storing data.
Answer
Data redundancy (the same data in many files) and data inconsistency (copies that disagree); also data isolation and dependence on file formats.
5.
Relation: STUDENT AdmNo | RollNo | Name | Section | City 1125 | 30 | Aarav | A | Pune 1478 | 31 | Chetan | A | Pune 1510 | 32 | Lakshmi | B | Pune 1586 | 33 | Bhavna | B | Patna 1634 | 34 | Asha | B | Kochi 1825 | 35 | Kavya | B | Patna 1972 | 36 | Lakshmi | B | Pune Find (a) its degree (b) its cardinality (c) its cardinality after 1 tuple is added and 5 deleted.
Answer
(a) 5; (b) 7; (c) 3
degree = columns; cardinality = rows; 7 + 1 − 5

Section C · long answer

6.
Explain five limitations of a file system and how a DBMS overcomes each.
Answer
Redundancy and inconsistency (a DBMS stores data once and links tables), data isolation (tables can be joined by keys), data dependence (programs use queries, not file layouts), uncontrolled sharing (a DBMS gives each user only the rights they need).

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In the app, every Database Concepts sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.

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