How SQL communicates with the database engine - Try It Yourself

How SQL Communicates with the Database Engine

📖 Scenario: You are working as a junior database assistant in a small company. Your task is to understand how SQL commands are sent to the database engine and how the engine processes these commands to give results.This project will guide you through creating a simple table, inserting data, and querying the data step-by-step to see how SQL communicates with the database engine.

🎯 Goal: Build a simple SQL script that creates a table, inserts data, and queries the data to demonstrate how SQL commands communicate with the database engine.

📋 What You'll Learn

Create a table named employees with columns id, name, and department

Insert three specific employee records into the employees table

Write a SQL query to select all employees from the employees table

Add a WHERE clause to filter employees by department

💡 Why This Matters

🌍 Real World

Understanding how SQL commands are structured and sent to the database engine helps you manage and query real databases effectively.

💼 Career

Database administrators and developers use these basic SQL commands daily to create, modify, and retrieve data from databases.

1

Create the employees table

Write a SQL statement to create a table called employees with three columns: id as an integer primary key, name as text, and department as text.

SQL

-- Your code here to create the employees table

Need a hint?

Use CREATE TABLE followed by the table name and define each column with its data type.

2

Insert employee records

Write three SQL INSERT INTO statements to add these employees to the employees table: (1, 'Alice', 'HR'), (2, 'Bob', 'IT'), and (3, 'Charlie', 'Finance').

SQL

CREATE TABLE employees (
    id INTEGER PRIMARY KEY,
    name TEXT,
    department TEXT
);
-- Your code here to insert employee records

Need a hint?

Use INSERT INTO employees (id, name, department) VALUES (...) for each employee.

3

Query all employees

Write a SQL SELECT statement to get all columns and all rows from the employees table.

SQL

CREATE TABLE employees (
    id INTEGER PRIMARY KEY,
    name TEXT,
    department TEXT
);

INSERT INTO employees (id, name, department) VALUES (1, 'Alice', 'HR');
INSERT INTO employees (id, name, department) VALUES (2, 'Bob', 'IT');
INSERT INTO employees (id, name, department) VALUES (3, 'Charlie', 'Finance');

-- Your code here to select all employees

Need a hint?

Use SELECT * FROM employees; to get all data.

4

Filter employees by department

Write a SQL SELECT statement to get all columns for employees where the department is 'IT'. Use a WHERE clause.

SQL

CREATE TABLE employees (
    id INTEGER PRIMARY KEY,
    name TEXT,
    department TEXT
);

INSERT INTO employees (id, name, department) VALUES (1, 'Alice', 'HR');
INSERT INTO employees (id, name, department) VALUES (2, 'Bob', 'IT');
INSERT INTO employees (id, name, department) VALUES (3, 'Charlie', 'Finance');

SELECT * FROM employees;

-- Your code here to select employees from IT department

Need a hint?

Use WHERE department = 'IT' to filter the results.