How the database engine processes a SELECT in SQL - Try It Yourself

How the database engine processes a SELECT

📖 Scenario: You are working with a small library database. You want to understand how the database engine processes a simple SELECT query to get book titles and authors.

🎯 Goal: Build a step-by-step SQL query that shows how the database engine processes a SELECT statement by creating a table, inserting data, selecting specific columns, and filtering results.

📋 What You'll Learn

Create a table named books with columns id, title, and author

Insert exactly three rows into the books table with given values

Write a SELECT query to retrieve only the title and author columns

Add a WHERE clause to filter books by a specific author

💡 Why This Matters

🌍 Real World

Understanding how SELECT queries work helps you retrieve exactly the data you need from databases in real applications like libraries, stores, or websites.

💼 Career

Database querying is a fundamental skill for data analysts, backend developers, and anyone working with data storage and retrieval.

1

Create the books table

Write a SQL statement to create a table called books with three columns: id as an integer primary key, title as text, and author as text.

SQL

-- Your code here to create the books table

Need a hint?

Use CREATE TABLE books and define the columns with their types.

2

Insert data into books

Insert these three rows into the books table: (1, 'The Hobbit', 'J.R.R. Tolkien'), (2, '1984', 'George Orwell'), and (3, 'To Kill a Mockingbird', 'Harper Lee'). Write three separate INSERT INTO statements.

SQL

CREATE TABLE books (
  id INTEGER PRIMARY KEY,
  title TEXT,
  author TEXT
);
-- Your code here to insert the three rows

Need a hint?

Use three INSERT INTO books statements with the exact values.

3

Select title and author columns

Write a SELECT query to get only the title and author columns from the books table.

SQL

CREATE TABLE books (
  id INTEGER PRIMARY KEY,
  title TEXT,
  author TEXT
);

INSERT INTO books (id, title, author) VALUES (1, 'The Hobbit', 'J.R.R. Tolkien');
INSERT INTO books (id, title, author) VALUES (2, '1984', 'George Orwell');
INSERT INTO books (id, title, author) VALUES (3, 'To Kill a Mockingbird', 'Harper Lee');

-- Your code here to select title and author

Need a hint?

Use SELECT title, author FROM books to get only those columns.

4

Filter books by author

Add a WHERE clause to the SELECT query to get only books where the author is 'George Orwell'.

SQL

CREATE TABLE books (
  id INTEGER PRIMARY KEY,
  title TEXT,
  author TEXT
);

INSERT INTO books (id, title, author) VALUES (1, 'The Hobbit', 'J.R.R. Tolkien');
INSERT INTO books (id, title, author) VALUES (2, '1984', 'George Orwell');
INSERT INTO books (id, title, author) VALUES (3, 'To Kill a Mockingbird', 'Harper Lee');

SELECT title, author FROM books
-- Your code here to add WHERE clause filtering author

Need a hint?

Add WHERE author = 'George Orwell' after the SELECT statement.