paper 3

Question 1

Database

Answer 1

An organized collection of data stored and accessed electronically.

Question 2

DBMS

Answer 2

Database Management System: software that creates, reads, updates, and deletes data in a database.

Question 3

Table (Relation)

Answer 3

A set of related data organized into rows (records) and columns (fields).

Question 4

Record (Tuple)

Answer 4

A single row in a table representing one real-world entity instance.

Question 5

Field (Attribute)

Answer 5

A column in a table representing one property of the entity.

Question 6

Domain

Answer 6

The set of all valid values for a given attribute.

Question 7

Primary Key

Answer 7

A field (or combination of fields) that uniquely identifies each record in a table.

Question 8

Foreign Key

Answer 8

A field in one table that references a primary key in another table to enforce relationships.

Question 9

Composite Key

Answer 9

A primary key made up of two or more fields combined.

Question 10

Entity

Answer 10

An object or concept about which data is stored (e.g., Student, Car).

Question 11

Relationship

Answer 11

An association between two entities (e.g., Student enrolls in Course).

Question 12

Cardinality

Answer 12

Specifies how many instances of one entity relate to instances of another (1:1, 1:M, M:N).

Question 13

1NF

Answer 13

First Normal Form: all fields contain only atomic (indivisible) values.

Question 14

2NF

Answer 14

Second Normal Form: all non-key fields depend on the whole primary key (no partial dependencies).

Question 15

3NF

Answer 15

Third Normal Form: no non-key field depends on another non-key field (no transitive dependencies).

Question 16

Data Integrity

Answer 16

Ensuring the accuracy and consistency of data over its lifecycle.

Question 17

Referential Integrity

Answer 17

Guarantee that foreign-key values match existing primary-key values (no orphan records).

Question 18

NOT NULL

Answer 18

Constraint that prevents a field from having empty (NULL) values.

Question 19

UNIQUE

Answer 19

Constraint that ensures all values in a field (or combination) are distinct.

Question 20

CHECK

Answer 20

Constraint that enforces a Boolean condition on field values (e.g., age ≥ 0).

Question 21

SELECT

Answer 21

Retrieve specified columns or all columns from a table (e.g., SELECT * FROM Students;).

Question 22

INSERT INTO … VALUES (…)

Answer 22

Add new rows to a table (e.g., INSERT INTO Students (name, age) VALUES (‘Alice’, 17);).

Question 23

UPDATE … SET … WHERE …

Answer 23

Modify existing rows in a table (e.g., UPDATE Students SET age = 18 WHERE name = ‘Alice’;).

Question 24

DELETE FROM … WHERE …

Answer 24

Remove rows from a table (e.g., DELETE FROM Students WHERE age < 16;).

Question 25

CREATE TABLE

Answer 25

Define a new table and its columns (e.g., CREATE TABLE Students (...);).

Question 26

DROP TABLE

Answer 26

Remove a table and its data from the database.

Question 27

WHERE

Answer 27

Filter rows based on a condition (e.g., WHERE age > 18).

Question 28

ORDER BY

Answer 28

Sort query results by one or more columns (e.g., ORDER BY age DESC).

Question 29

GROUP BY

Answer 29

Group rows sharing a value for aggregate calculations (e.g., GROUP BY major).

Question 30

LIMIT

Answer 30

Restrict the number of rows returned by a query (e.g., LIMIT 5).

Question 31

*

Answer 31

Wildcard meaning “all columns” in a SELECT statement.

Question 32

%

Answer 32

Wildcard in LIKE patterns matching any sequence of characters.

Question 33

_

Answer 33

Wildcard in LIKE patterns matching exactly one character.

Question 34

;

Answer 34

Statement terminator; marks the end of an SQL command. (e.g., SELECT * FROM Students; )

Question 35

COUNT()

Answer 35

Aggregate function returning the number of rows matching criteria.

Question 36

SUM()

Answer 36

Aggregate function returning the total sum of a numeric column.

Question 37

AVG()

Answer 37

Aggregate function returning the average value of a numeric column.

Question 38

MIN()

Answer 38

Aggregate function returning the smallest value in a set.

Question 39

MAX()

Answer 39

Aggregate function returning the largest value in a set.

Question 40

LIKE

Answer 40

Operator for pattern matching with % and _ wildcards.

Question 41

Why normalize databases?

Answer 41

To reduce redundancy and prevent update, insert, and delete anomalies, ensuring integrity and efficient storage.

Question 42

How is data consistency maintained?

Answer 42

Via constraints (PK, FK, NOT NULL, UNIQUE, CHECK), referential integrity, and a well-normalised schema.

Question 43

<>

Answer 43

Inequality operator; selects rows where the value is not equal to the specified one. (e.g., SELECT * FROM Students WHERE grade <> 'A'; )

Question 44

DISTINCT

Answer 44

Removes duplicate values from the result set, returning only unique entries. (e.g., SELECT DISTINCT major FROM Students; )

Question 45

DESC

Answer 45

DESC

Question 46

ASC

Answer 46

Specifies ascending sort order in an ORDER BY clause (default if omitted). (e.g., SELECT * FROM Students ORDER BY age ASC;)