Option A - Database (Paper 2)

Question 1

What is the difference between data and information?

Answer 1

Data is meaningless; it must be interpreted to produce information.

Question 2

What is the difference between an information system and a database?

Answer 2

A database is a structured collection of data (e.g., tables storing student records).

An information system is a broader system that uses databases along with people, hardware, software, and procedures to collect, process, store, and share information (e.g., a school management system).

Databases are a component within an information system.

Question 3

Why are databases needed?

Answer 3

They enable benefits such as data sharing and maintaining correct information relating to customers and/or clients.

Question 4

How do transactions maintain data consistency?

Answer 4

Transactions involve completing two operations to ensure consistency; if one fails, the transaction is rolled back.

Question 5

Define the term database transaction.

Answer 5

A database transaction is a sequence of operations performed as a single logical unit of work.

Question 6

What is concurrency in a data sharing situation?

Answer 6

Concurrency refers to the ability of multiple users to access and modify the database simultaneously.

Question 7

What does ACID stand for in database transactions?

Answer 7

• Atomicity
• Consistency
• Isolation
• Durability

Question 8

What are the two functions that databases require?

Answer 8

• Query functions
• Update functions

Question 9

What is the role of data validation?

Answer 9

Data validation ensures that the data entered into the database meets certain criteria.

It makes sure that the data entered is in the appropriate range and/or type to
avoid obtaining incorrect results;
It is performed by the computer which detects if data entered is not in the
range/of the type which is defined (by the person who set up the database);

Question 10

What is a database management system (DBMS)?

Answer 10

A DBMS is software that interacts with the database, allowing for creation, manipulation, and interrogation. Creates and stores the databse.

Question 11

What is a relational database management system (RDBMS)?

Answer 11

An RDBMS is a type of DBMS that is based on the relational model. In rows and columns (table format)

Question 12

What are the functions and tools of a DBMS?

Answer 12

They include management functions for creation, manipulation, and interrogation of a database.

Question 13

How can a DBMS promote data security?

Answer 13

Through features like data validation, access rights, and data locking.

Access Rights Description: Passwords and PIN numbers limit the access to private information to
authorized users only;

Question 14

Define the term schema.

Answer 14

A schema is the blueprint that defines the structure, organization, and relationships of data within a database, encompassing tables, columns, constraints, and relationships

Question 15

What are the three levels of schema?

Answer 15

• Conceptual
• Logical
• Physical

Question 16

What is a data dictionary?

Answer 16

A data dictionary is a centralized repository of information about data, including its meaning, relationships, and usage.

Question 17

Why is a data definition language important?

Answer 17

It is crucial for implementing a data model by defining the structure of the database.

Question 18

What is the importance of data modeling in database design?

Answer 18

Data modeling helps in structuring data and understanding the relationships between different data entities.

Question 19

Define the following database terms: table, record, field.

Answer 19

• Table: equivalent to relation/file
• Record: equivalent to tuple/row
• Field: equivalent to attribute/column

Question 20

What are the different types of relationships within databases?

Answer 20

• One-to-one
• One-to-many
• Many-to-many

Question 21

What issues are caused by redundant data?

Answer 21

Redundant data can lead to integrity and reliability issues.

Question 22

What is referential integrity?

Answer 22

Referential integrity ensures that relationships between tables remain consistent. Fosters reliability and integrity of the data.

Question 23

What are the differences between 1st Normal Form (1NF) and 2nd Normal Form (2NF)

Answer 23

• 1NF: no repeating rows or columns
• 2NF: based on full functional dependency

Question 24

What is Normalization? What are the characteristics of a normalized database?

Answer 24

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity. A normalized database reduces redundancy and dependency.

Question 25

What is the importance of selecting appropriate data types?

Answer 25

Selecting the correct data type is crucial for data integrity and efficiency.

Question 26

What is an entity-relationship diagram (ERD)?

Answer 26

An ERD is a visual representation of the relationships among entities in a database.

Question 27

Describe the use of transactions

Answer 27

Transactions ensure that a series of database operations are completed successfully as a single unit. If any part fails, the entire transaction is rolled back to maintain data integrity and data consistency.

Question 28

Explain the importance of the ACID properties of a database transaction

Answer 28

ACID stands for Atomicity, Consistency, Isolation, and Durability. These properties ensure: Atomicity: all or none of the operations occur, Consistency: data remains valid after the transaction, Isolation: concurrent transactions don’t interfere, Durability: once committed, changes are permanent.

Question 29

What is the difference between a database and a relational database?

Answer 29

A database stores data, but it may not follow any specific structure. A relational database stores data in tables with relationships between them using keys, following the relational model.

Question 30

Discuss the need for databases

Answer 30

Databases are needed to store, organize, and manage large amounts of data efficiently, enabling easy retrieval, updating, and sharing of information across systems.

Question 31

Explain the role of data verification

Answer 31

Data verification ensures that the data entered into the system matches the original source, reducing input errors. It helps maintain accuracy and reliability of data.

Question 32

What is a primary key, and can you provide an example?

Answer 32

A primary key is a unique identifier for each record in a database table, ensuring no two rows have the same value and no null values are allowed. Example: In a table "Students" with columns "StudentID," "Name," and "Age," the "StudentID" (e.g., S001, S002) can be the primary key, uniquely identifying each student.

Question 33

What is a secondary key, and can you provide an example?

Answer 33

A secondary key is a non-unique field or set of fields used to improve search efficiency, often indexed but not necessarily unique. Example: In the "Students" table, the "Name" column (e.g., John, Sarah) could be a secondary key to quickly search for students by name, even though names may repeat.

Question 34

What is a foreign key, and can you provide an example?

Answer 34

A foreign key is a column or set of columns in one table that references the primary key of another table, establishing a relationship between them. Example: In a table "Enrollments" with columns "EnrollmentID," "StudentID," and "CourseID," the "StudentID" column is a foreign key that references the "StudentID" primary key in the "Students" table.

Question 35

What is a candidate key, and can you provide an example?

Answer 35

A candidate key is a column or set of columns that can uniquely identify each record in a table, from which the primary key is chosen. Example: In the "Students" table, both "StudentID" (e.g., S001, S002) and "Email" (e.g., john@example.com, sarah@example.com) could be candidate keys if both are unique, but only one (e.g., "StudentID") is selected as the primary key.

Question 36

What is a composite primary key, and can you provide an example?

Answer 36

A composite primary key is a primary key made up of two or more columns to uniquely identify each record in a table, used when no single column is unique. Example: In a table "OrderDetails" with columns "OrderID," "ProductID," and "Quantity," the combination of "OrderID" (e.g., O101) and "ProductID" (e.g., P201) forms a composite primary key to uniquely identify each order-product pair.

Question 37

What is a tuple and what is an attribute in a table?

Answer 37

A tuple is a row (a record). An attribute is a column (a field)

Question 38

What is a super key, and can you provide an example?

Answer 38

A super key is a set of one or more columns in a table that uniquely identifies each record, including any combination that contains a candidate key. Example: In a "Students" table with columns "StudentID," "Name," and "Email," the combination of "StudentID" (e.g., S001) and "Name" (e.g., John) is a super key because it uniquely identifies each student, even though "StudentID" alone would suffice.

Question 39

What is a composite key, and can you provide an example?

Answer 39

A composite key is a key made up of two or more columns to uniquely identify each record in a table, often used when no single column is unique. Example: In a "ClassSchedule" table with columns "CourseID," "RoomID," "TimeSlot," and "Day," the combination of "CourseID" (e.g., C101) and "TimeSlot" (e.g., 10AM) forms a composite key to uniquely identify each scheduled class.

Question 40

What is physical schema?

Answer 40

Describes how data is physically stored on storage devices (e.g., files, indexes, memory layout).

Question 41

What is conceptual schema?

Answer 41

Defines the overall structure and organization of the entire database (e.g., entities, relationships), independent of physical storage.

Question 42

What is logical schema?

Answer 42

Specifies the structure of the data as seen by the DBMS, including tables, columns, data types, and constraints.

Question 43

Advantages of database schema

Answer 43

- Providing Consistency of data - Maintaining Scalability - Performance Improvement - Easy Maintenance - Security of Data

Question 44

What do ACID properties do?

Answer 44

Ensure that the transaction get executed successfully and its effect permanently stored in the database. If the transaction is rolled back, it must return the database to its last consistent state before the update.

Question 45

Outline what is meant by data redundancy.

Answer 45

Some data in a database can be found in two or more different locations / several copies of the same data; Which takes up unnecessary space; Data that is stored could be calculated from other data items; Unused data;

Question 46

Queries of DDL and DML (roles of each)

Answer 46

DDL (Data Definition Language) -> Create, Drop, Alter, Truncate -> defines or modifies database structure. DML (Data Manipulation Language) -> Insert, Update, Delete -> manipulates data in the database.