DISTINCT for unique values in SQL - Mini Project: Build & Apply

Using DISTINCT to Find Unique Values in SQL

📖 Scenario: You work at a bookstore that keeps track of all book sales in a database table called sales. Each sale record includes the book_title and the customer_name. Sometimes customers buy the same book multiple times.Your manager wants to know the list of unique book titles sold so far, without duplicates.

🎯 Goal: Build an SQL query that uses DISTINCT to find all unique book titles from the sales table.

📋 What You'll Learn

Create a table called sales with columns book_title and customer_name.

Insert the exact sales data provided.

Write a query that selects unique book titles using DISTINCT.

Order the results alphabetically by book_title.

💡 Why This Matters

🌍 Real World

Bookstores and many businesses use DISTINCT to find unique items, customers, or transactions in their databases.

💼 Career

Knowing how to use DISTINCT helps database analysts and developers write queries that avoid duplicate data and produce clean reports.

1

Create the sales table and insert data

Create a table called sales with columns book_title and customer_name, both as text. Then insert these exact rows into sales: ('The Hobbit', 'Alice'), ('1984', 'Bob'), ('The Hobbit', 'Charlie'), ('Dune', 'Alice'), ('1984', 'David').

SQL

-- Create the sales table and insert the given rows
-- Your code here

Need a hint?

Use CREATE TABLE to define the table and INSERT INTO to add rows.

2

Set up the SELECT statement

Write a SELECT statement to get the book_title column from the sales table. Do not add DISTINCT yet.

SQL

CREATE TABLE sales (
    book_title TEXT,
    customer_name TEXT
);

INSERT INTO sales (book_title, customer_name) VALUES
('The Hobbit', 'Alice'),
('1984', 'Bob'),
('The Hobbit', 'Charlie'),
('Dune', 'Alice'),
('1984', 'David');

-- Write a SELECT statement to get book_title from sales
SELECT book_title FROM sales;

Need a hint?

Use SELECT book_title FROM sales to get all book titles.

3

Add DISTINCT to get unique book titles

Modify the SELECT statement to use DISTINCT so it returns only unique book_title values from the sales table.

SQL

CREATE TABLE sales (
    book_title TEXT,
    customer_name TEXT
);

INSERT INTO sales (book_title, customer_name) VALUES
('The Hobbit', 'Alice'),
('1984', 'Bob'),
('The Hobbit', 'Charlie'),
('Dune', 'Alice'),
('1984', 'David');

-- Add DISTINCT to select unique book titles
SELECT DISTINCT book_title FROM sales;

Need a hint?

Add the keyword DISTINCT right after SELECT to get unique values.

4

Order the unique book titles alphabetically

Add an ORDER BY clause to the query to sort the unique book_title values alphabetically in ascending order.

SQL

CREATE TABLE sales (
    book_title TEXT,
    customer_name TEXT
);

INSERT INTO sales (book_title, customer_name) VALUES
('The Hobbit', 'Alice'),
('1984', 'Bob'),
('The Hobbit', 'Charlie'),
('Dune', 'Alice'),
('1984', 'David');

-- Add ORDER BY to sort book titles alphabetically
SELECT DISTINCT book_title FROM sales ORDER BY book_title ASC;

Need a hint?

Use ORDER BY book_title ASC to sort the results alphabetically.