Databases

​The power of Databases

​A database is an organised way to store huge amounts of data, making it possible to search for specific information and generate reports. A report is the result of a database query, which is a way to interrogate the database.

Non-Relational

Relational

Databases can be classified as or

Non-Relational Databases

​Non-relational databases, are a type of DBMS that aren't based on the traditional relational database model. Unlike relational databases, which use a structured schema and tables to organize data, non-relational databases are more flexible and can handle various types of data models.

Non-Relational Databases

Non-relational databases may not use SQL (Structured Query Language) for querying data. Instead, they often provide their own query languages.

Multiple Choice

What is a Database Management System (DBMS)?

• A type of spreadsheet for organizing data
  

• A software that manages and organizes large amounts of data
  

• A programming language for creating databases

• A tool for generating reports in a database

Multiple Choice

What is a report in the context of a database?

• A way to organize data sequentially

• A file containing raw data

• A type of database table

• The result of a database query

Multiple Choice

What does SQL stand for?

• Spreadsheet Query Language
  

• Structured Query Languge

• System Question Language

• Structured Query Language

Non-Relational Databases

​Non-relational databases can be classified as follows:

• Flat-file database

• Network database

• Object-oriented database

Non-Relational Databases

• Flat-file database: A flat-file database stores data in a tabular form, usually a plain text file or a spreadsheet. Each line of the file represents a record, and each field within the record is separated by a delimiter, such as a comma.

Non-Relational Databases

• Example: A CSV (Comma-Separated Values) file is a common example of a flat-file database, where each line represents a record (set of data) and fields are separated by commas.

Consider a simple database storing information about students in a school. The flat-file database, in this case, is a CSV file named "students.csv": In this example, each line represents a student's record, and the fields (ID, Name, Grade) are separated by commas.

Multiple Choice

What is a characteristic of flat-file databases?

• Organizes data in tables with relationships

• Stores data sequentially in a single table

• Uses a graph structure for data representation

• Utilizes object-oriented principles

Non-Relational Databases

• Network database: are a type of database management system that organizes data using a network model. In this model, data is represented as nodes (records) and links (relationships) between nodes. The network model allows for more complex relationships than the hierarchical model. Records can have multiple parent and child records, forming a graph-like structure.

• Example: Integrated Data Store (IDS)

Non-Relational Databases

• In this Uni we have the Maths and Computer Dep., they both share the library and the computer lab and are linked with one another as they share data.

Multiple Choice

How are entities organized in a network database?

• As objects in classes

• Sequentially in one table

• In a graph with complex relationships

• Using primary and foreign keys

Multiple Choice

What type of relationship structure can be found in a network database?

• Hierarchical
  

• Flat

• Table-based

• Graph-like

• Circular-linked

Non-Relational Databases

• Object-oriented database: is a type of database that stores data in the form of objects rather than tables and rows. These objects are stored and organized in a way that reflects the relationships and structures found in the real world.

Non-Relational Databases

• Object-oriented database: the objects which belong to a

  class and are defined by a method. For example, the object "oak' belongs to the class 'tree' and has certain characteristics.

Imagine you have a computer system to manage a zoo. In a traditional database, you might have separate tables for animals, caretakers, and other details. In an object-oriented database, you'd treat each thing in the zoo (like animals or caretakers) as an "object" with its own characteristics and behaviors.

For example, an animal object could have attributes like species and habitat, and a caretaker object could have a name and a list of animals they care for. The database then stores these objects directly, reflecting the real-world relationships between them.

Let's visualize this with a simple representation:

In this simplified visual, you have an object for an animal (Lion) with its species and habitat, and another object for a caretaker (John) with their name and a list of responsibilities (caring for the Lion). This is a basic example of how objects in an object-oriented database can represent real-world entities and their relationships.

Multiple Choice

What is a key feature of object-oriented databases?

• 5. Rigid schema with predefined relationships

• 5. Storing data as objects with methods

• 5. Organizing data sequentially in tables

• 5. Relational model with primary and foreign keys

Multiple Choice

In an object-oriented database, what is an example of an object and its class?

• 5. "Tree" and "Oak"

• 5. "Oak" and "Table"

• 5. "Database" and "Report"

• 5. "Graph" and "Network"

RELATIONAL DATABASES

A relational database stores information in separate tables and files, and data is organised in fields and records. All the data is linked together by key fields and a DBMS (Database Management System) which controls who can access what (e.g. some employees may have restricted access to company data).

Relational Databases

The key field contains an item of data that is unique to that record, so no records have the same value in the key field.

Relational Databases

In summary, the field name is a label for a column, helping users understand the nature of the data it contains, while the key field is a specific column used to uniquely identify each record in a table.

Relational Databases

Multiple Choice

What is the primary function of a key field in a relational database?

• Provide a label for data columns
  

• Uniquely identify records

• Define the data type of a field

• Control access to the database

Multiple Choice

Why is the data type of a field crucial when creating a database?

• To define the field's label
  

• To determine the format of the field

• To identify the contents of the field

• To perform specific processes on the data

Multiple Choice

What is the purpose of a Database Management System (DBMS) in a relational database?

• Controlling access to data
  

• Designing table layouts

• Defining data types

• Creating queries

Which language do Rel-Databases use?

Recap...

• Relational databases: Store data in separate tables and files, organized by relationships.
• Network databases: Organize data in a graph with complex relationships.
• Object-oriented databases: Store data as objects with defined characteristics.

Recap...

• Flat-File Database: A database where all data is organized sequentially and into one single table, suitable for smaller-scale applications.

• SQL (Structured Query Language):The language used for querying relational databases, providing a powerful and flexible means to retrieve and manipulate data.

Recap...

• Database Management System (DBMS):

  • Role: Controls access to the database, manages relationships, and ensures data integrity.

  • Example: In relational databases, a DBMS uses key fields to link data and control access permissions.

Word Cloud

Write examples of Relational-Databases.

Examples of Rel-Databases.

1. MySQL

2. Oracle Database

3. Microsoft SQL Server

4. PostgreSQL

5. SQLite

6. IBM Db2

Multiple Choice

What language is commonly used to create queries in relational databases?

• Java

• Python

• SQL

• C++

Creating a Database

The first step in creating a database is to decide what fields you need for each table. Then, each field needs a name, a description of its contents, a data type and format. Data type is very important, as different processes can be performed on different types of data.

The most common data types are: text (e.g. characters), integers (i.e. whole numbers such as 18), real numbers (e.g. 11.36), dates (e.g. 20/10/16).

Creating a Database

• Step 1: Determine fields for each table

• Step 2: Assign name, description, data type, and format to each field

• Data Types: text, integers, real numbers, dates.

Multiple Choice

Which data type represents whole numbers in a relational database?

• Real Numbers
  

• Text

• Dates

• Integers