Adventures in Machine Learning

Flask and SQLite DB: Building a Simple CRUD Application

Flask is a popular Python web framework that offers flexibility and simplicity in developing web applications. One of the most common types of web applications is a CRUD application, which stands for Create, Retrieve, Update, and Delete.

In this article, we will explore how to create a CRUD application using Flask and SQLite DB, particularly through coding the and the main Application. We will take a closer look at each of the CRUD operations and the associated views (Create, Retrieve, Update, and Delete) and discuss the necessary code to implement them.

1) Flask CRUD Application

What is a CRUD application? A CRUD application is a type of web application that allows users to perform four fundamental operations, which are create, retrieve, update, and delete.

With a CRUD application, users can add, view, modify, and delete data from a database or file. Coding the

Flask applications often use a database to store their data, and we can use Flask_SQLAlchemy to connect and interact with a database.

In this process, we should create a Model to represent the database table.

Coding the main Application

Once we have specified the model structure, we can create the main application file to launch the web application. We need to first initialize an instance of the SQLite database and then create the database tables we defined in the file.

Coding the Create view

To create a new item in the database, we need a form that allows users to input the necessary data and a view function associated with the form to receive and store these data. We can create an HTML form with text input boxes for the employee’s ID, name, age, and position.

Coding the Retrieve views

Retrieving data from the database is the core function of any CRUD application. There are two ways to retrieve data from the database – either retrieve all the data or retrieve a single item.

We can use RetrieveDataList to retrieve all the data and display them in a list format.

Coding the Update View

Updating an element in the database requires modifying the data in the database with new data provided by the user. We create a new HTML form similar to the Create view to help users update employee details.

Coding the Delete View

The Delete function is responsible for removing a particular record from the database. It needs verification from the user to determine if they indeed want to delete the selected data, which we can implement with an HTML form.

2) Flask_SQLAlchemy and SQLite DB

Definition of Flask_SQLAlchemy

Flask_SQLAlchemy is a Flask extension that provides a simple and efficient way to interact with SQL databases. It allows for hassle-free object-relational mapping (ORM) and can map to a wide range of databases, including SQLite, MySQL, PostgreSQL, and Oracle.

Definition of SQLite DB

SQLite is a serverless and self-contained relational database management system (RDBMS) that employs a small, efficient, and fast engine. SQLite stores all data in files on the disk, making it easy to manage because there is no separate server process.


In summary, Flask and SQLite DB provide flexible and straightforward ways to create a CRUD application. By following our step-by-step guide to coding each view, you should be able to create your own simple CRUD application from scratch.

With Flask_SQLAlchemy, we can easily define our database table structure, connect to a database and interact with it. Meanwhile, SQLite DB offers an intuitive and lightweight solution for managing data in web applications.

Through the combination of Flask and SQLite DB, developers can quickly develop, test, and deploy their web applications with ease. In summary, this article explored the creation of a CRUD application using Flask and SQLite DB.

The article outlined the essential elements of coding a CRUD application, including the creation of, the main Application, and the implementation of the Create, Retrieve, Update, and Delete Views. Additionally, we discussed the importance of Flask_SQLAlchemy in aiding the interaction with databases and the fundamental properties of SQLite DB.

The amalgamation of Flask and SQLite DB gives developers an efficient and straightforward option for managing and designing web applications. In closing, this article serves as a valuable guide for aspiring developers looking to create an effective CRUD application using Flask and SQLite DB.

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