Database Essentials using Postgres - Writing Basic SQL Queries - Overview of Data Model

This article aims to provide beginners with a comprehensive guide on writing SQL articles. We will cover key concepts, provide step-by-step instructions, offer hands-on tasks, and discuss the importance of the accompanying video.

Key Concepts Explanation

Key Concept 1

In SQL, SELECT is used to retrieve data from a database. Here is an example of a simple SELECT statement:

SELECT * FROM table_name;

Key Concept 2

Another important concept is WHERE clause, which filters data based on a specified condition. Here’s an example:

SELECT * FROM table_name WHERE condition;

Hands-On Tasks

Here are some hands-on tasks for you to practice SQL commands:

  1. Write a SELECT statement to retrieve all columns from a table.
  2. Use a WHERE clause to filter data based on a specific condition.


In conclusion, writing SQL articles requires a clear understanding of key concepts and the ability to present them in an engaging manner. Remember to practice writing SQL queries regularly and seek feedback from the community to improve your skills.

Overview of Data Model

We will be using a retail data model for this section. It contains 6 tables:

  • Orders
  • Order_items
  • Products
  • Categories
  • Departments
  • Customers

The tables have various relationships between them, such as 1 to many relationships between Orders and Order_items, Products and Order_items, and Customers and Orders. Additionally, there are hierarchical relationships from Departments to Products through Categories. Understanding these relationships is essential for effective SQL querying.

Watch the video tutorial here