Setting Up Your SQLite Practice Database in VS Code

Install the SQLite VS Code extension, create an employee database, populate it with 25 sample records, and verify everything is working.

Before you can practice SQL queries, you need a real database with real data. This guide walks you through installing the SQLite extension for Visual Studio Code, creating a department and employee table, and loading 25 sample employees across five departments. One of those employees deliberately has no department assigned — you’ll use that record later to practice LEFT JOIN and IS NULL queries.

Prerequisites

You need Visual Studio Code and the following extension:

• SQLite by Alex Covizzi (search for alexcovizzi.vscode-sqlite in the Extensions panel)

The extension lets you:

• Create and open .db database files
• Execute SQL scripts directly from the editor
• Browse tables and their schemas
• View and edit records with a graphical interface

Database Schema Diagram

Department
──────────────────
department_id  (PK)
department_name
       ▲
       │ department_id (FK)
       │
Employee
──────────────────
employee_id    (PK)
employee_name
salary
city
joining_date
department_id  (FK)

Sample Queries to Try Now

Once your database is set up, practice these queries to make sure everything is working:

Display all employee names:

SELECT employee_name
FROM employee;

Display employees from Hyderabad:

SELECT *
FROM employee
WHERE city = 'Hyderabad';

Display employees earning more than ₹70,000:

SELECT *
FROM employee
WHERE salary > 70000;

Display employees sorted by salary (highest first):

SELECT employee_name, salary
FROM employee
ORDER BY salary DESC;

Join employees with their department names:

SELECT
    e.employee_name,
    d.department_name
FROM employee e
INNER JOIN department d
ON e.department_id = d.department_id;

Show all employees, including those without a department:

SELECT
    e.employee_name,
    d.department_name
FROM employee e
LEFT JOIN department d
ON e.department_id = d.department_id;

Run the LEFT JOIN query and compare its output to the INNER JOIN. Notice that Gopal Krishna appears in the LEFT JOIN result with NULL for department_name, but is absent from the INNER JOIN result. This is the key difference between the two join types.

What You’ve Accomplished

You have:

• Installed the SQLite extension in Visual Studio Code
• Created a employee.db SQLite database file
• Defined the department and employee tables with appropriate constraints and a foreign key relationship
• Inserted 5 departments and 25 employee records (including one with a NULL department)
• Verified the data with count and selection queries
• Run your first JOIN queries

Your database is now ready for all the SQL topics covered in the next chapters — SELECT, WHERE, GROUP BY, HAVING, JOINs, aggregate functions, and window functions.