PowerPoint 1

Question 1

What’s a database?

Answer 1

A database is an organized collection of structured information or data, typically stored electronically in a computer system.

Question 2

What is a DBMS?

Answer 2

A database management system is what controls databases

Question 3

Why are databases often modeled in rows and columns in a series of tables?

Answer 3

To make processing and data querying efficient.

Question 4

What is SQL?

Answer 4

SQL is a programming language used by nearly all relational databases(RDBs) to query, manipulate, define data and to provide access control.

Question 5

What is a Database Software used for?

Answer 5

Database software is used to create, edit, and maintain database files and records (, enabling easier file and record creation, data entry, data editing, updating, and reporting.)

The software also handles data storage, backup and reporting, multi-access control, and security.

Question 6

Name the 5 types of databases

Answer 6

1. Relational Databases(RDBs)
2. Object-oriented Databases(OODBs)
3. Data warehouses
4. Non-Relational Databases
5. Graph databases

Question 7

What is a relational database?

Answer 7

A relational database is a type of database where Items are organized as a set of tables with columns and rows.

Question 8

What is a Object-oriented database?

Answer 8

Object-oriented databases are databases where information is represented in the form of objects, as in object-oriented programming

Question 9

What is a data warehouse?

Answer 9

A database that contains multiple databases.
A central repository for data, a data warehouse is a type of database specifically designed for fast query and analysis.

Question 10

What is a Non-Relational Database?

Answer 10

A NoSQL, or nonrelational database, allows unstructured and semi structured data to be stored and manipulated (in contrast to a relational database, which defines how all data inserted into the database must be composed).

Question 11

What is a Graph Database?

Answer 11

A graph database stores data in terms of entities and the relationships between entities.​

A sort of NoSQL Database System

Question 12

What are the benefits of using RDBMs?

Answer 12

1. Data Consistency
2. Commitment and atomicity

Question 13

What are ACID properties?

Answer 13

ACID properties are a set of rules that databases follow to provide a reliable and consistent environment for managing data and executing transactions.

These 4 properties are:
1. Atomicity
2. Consistency
3. Isolation
4. Durability

Question 14

What is Atomocity?

Answer 14

Atomicity defines all the element that make up a complete database transaction.

Question 15

What is Consistency?

Answer 15

Defines the rules for maintaining data points in a correct state after a transition.

Question 16

What is Isolation?

Answer 16

Keeps the effect of a transaction invisible to others until it is committed, to avoid confusion.

Question 17

What is Durability?

Answer 17

Ensures that data changed becomes permanent once the transaction is committed.

Question 18

What will a well designed database do?

Answer 18

1. Eliminate data redundancy
2. Ensure data integrity and accuracy

Question 19

What is meant by eliminating data redundancy?

Answer 19

That the same piece of data shall not be stored in more than one place. This is because duplicate data not only wastes storage, but can also lead to inconsistencies.

Question 20

What are data models?

Answer 20

Conceptual tools to describe data.

Question 21

What is an entity?

Answer 21

An entity can be a real-world object, that can easily be indentifiable.

example:
In a school database:
students, teachers, classes and courses offered can be considered as entities.

Question 22

What is an attribute?

Answer 22

Things that can describe an entity

example:
student name, age, birthday, etc.

Question 23

What is a relationship?

Answer 23

The association among entities

example:
An employee works at a department

Question 24

Define Cardinality and the three main cardinal relationships

Answer 24

Cardinality defines the numerical attributes of the relationship between two entities or entity sets.

The three main cardinal relationships:
1. one-to-one relationships
2. one-to-many relationships
3. many-to-many relationships

Question 25

What are the steps for designing a relational database?

Answer 25

1. Define the purpose of the Database (Requirement Analysis)
2. Gather data, organize it in tables and specify all the primary keys
3. Create relationships amongst tables
   (foreign keys)
4. Refine and Normalize the design

Question 26

What is normalizing and why do it?

Answer 26

Normalizing is the process of organizing the data within a database

We normalize databases to reduce redundancy and to ensure only related data is stored in each table

Question 27

What is normalizing and why do it?

Answer 27

Normalizing is the process of organizing the data within a database

We normalize databases to reduce redundancy and to not waste space.

Question 28

What are data anomalies and what kind of data anomalies are there?

Answer 28

Anomalies are irregularities or deviations from the expected patterns in a dataset, often indicating errors, inconsistencies, or unusual occurrences in the data.

The three kinds of data anomalies are:
1. Delete anomaly
2. Insert anomaly
3. Update anomaly

Question 29

Explain what a delete anomaly is

Answer 29

This occurs when deleting data from a database removes unintended data.

Example:
If a table contains customer orders and their details, deleting a row for an order might accidently delete information about the customer who placed the order as well.

Question 30

Explain what an insert anomaly is

Answer 30

This occurs when it is not possible to add data to the database because some required data is missing.

Example:
If a table has a primary key and some attributes that are dependent on that key, attempting to insert a row without the primary key value will result in an insertion anomaly.

Question 31

Explain what an update anomaly is

Answer 31

This occurs when updating one piece of data in a database causes inconsistencies in other parts of the database.

Example:
If a customer changes their address, and that address is stored in multiple databases, updating in one table but not in another would result in an update anomaly.

Question 32

What are Normal Forms and what levels of normalization are there?

Answer 32

Normal forms are a series of guidelines that help to ensure that the design of a database is efficient, organized, and free from data anomalies.
There are several levels of normalization, each with its own set of guidelines, known as normal forms.

The different levels of normalization:
1. First Normal Form(NF1)
2. Second Normal Form(NF2)
3. Third Normal Form(NF3)
4. Fourth Normal Form(NF4)
5. Boyce-Codd Normal Form (BCNF)
6. Fifth Normal Form(NF5)