Comprehension of Database Architecture
Certain queries need to be addressed before one delves into the implementation details of a database. These include the scope, scale, and purpose of the database. The focus of this section is the functionality of a relational database management system. So at its most basic, we could say that the purpose of a database is to store tables. Structures are built to hold information within a table, unlike its rows and columns. The rows serve as unique records and the columns hold data description for each individual.Let us illustrate: for instance, you have a web application that enables users to register and create accounts. If you consider this scenario, almost every application has a User table which consists of the details of all the users who have registered. The primary concept is, by placing data into tables, data is easiest to receive and provide more efficiently.
Identifying the Requirements
Identifying the Requirements alongside website functionalities is essential as the first step when creating a sample database for web application is when considering what kind of data the sample web application is going to be dealing with. For instance, if the web application in question is a social media one, there might be a need in the database: a system table for users, a system table for posts made by users, another for comments posted under a post, and another one that enables liking posts or even following users. A blog that is straightforward, on the other hand, is barely going to need a single one which is for the username and another which would accommodate the blog post.This clarifies the aim of the database and helps you in determining which tables are required, how those tables will relate, and what kind of data will be stored in these tables. For example, if a post on a social media application is created by a single user account, a single person is the author of a post, and the number of posts that user authors can be multiple. Within that post, required could be the number of comments made, which can also be more than one. This relationship of users, posts, and comments can be represented with the help of multiple tables and relational database principles which shall be discussed further.
Normalisation of the Database
In the Database Management System, normalisation is one of the key concepts. Normalisation is the process of organizing the data in the database in such a way that it reduces redundancy and dependency. By removing duplicate data and ensuring that related tables are designed in such a way that relevant data is present in the corresponding tables, performance and extensibility of the database is improved.There are various normal forms in database normalization; however, the first, second, and third normal forms are the most widely used.
First Normal Form (1NF)
The table with the specification in its columns ensures that each cell in the column is atomic. It is not permissible for a column to contain more than one atomic value.Second Normal Form (2NF)
The instruction is that all non-key attributes are fully functionally dependent on the primary key of the table.Third Normal Form (3NF)
States that all the non-key attributes are only dependent on the key attribute and no other non-key attribute.There are key aspects that achieve balance between efficiency and effectiveness of the database. Complex tables are easier to build with diagrams and can cut down on the table count but may result in performance lags at times. Understanding the performance enhancement that must be prioritized and the efficiency that must be compromised is crucial to building a successful database.
How Relationships are Created Between Tables
Establishing relationships between tables is one of the important concepts of relational databases. This allows the database to find relevant information quickly and efficiently. In the case of a typical web application, there are three main types of relationships that you may encounter:1. One-to-One Relationships
This happens when one record in one table corresponds to exactly one record in another table. For example, if each user had only one profile picture, then there would be a ‘Users’ table and a ‘ProfilePictures’ table, and a picture would be taken of the relationship between the two (one to one).2. One-to-Many Relationships
This is the most common type of relationship that you will encounter in the web application. This happens when one record in one table corresponds to several records in another table. For instance, one user may write several posts, so between the ‘Users’ and the ‘Posts’ there would be a one-to-many relationship.3. Many-to-Many Relationships
This type of relationship occurs when a number of records in one table relate to a number of records in another table. In many cases, for example, a user can have many followers and a follower can follow a number of users. It has been seen that such a type of relationship needs a 3rd table that is often called a ‘junction table’ to cater for the many-to-many relationships.Establishing the appropriate table relationships facilitates the undertaking of complex data manipulations within the web application while guaranteeing a high level of data correctness.
Working with Data Integrity
Data integrity means the accuracy and consistency of the data held in a database. Location of data on a web application calls for data to be accurate and dependable, therefore data integrity has to be upheld. There are various methods of ensuring integrity of data in SQL databases.One of the ways that significantly aid in maintaining the integrity of data is the use of constraints. These are the rules that govern the data types that can be injected into a table in a relational database. They include the following:
