IN and NOT IN operators in MySQL - Mini Project: Build & Apply

Using IN and NOT IN Operators in SQL

📖 Scenario: You are managing a small bookstore database. You want to find books by certain authors and exclude others.

🎯 Goal: Build SQL queries using IN and NOT IN operators to filter books by author names.

📋 What You'll Learn

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

Insert specific book records into the books table

Write a query using IN to select books by given authors

Write a query using NOT IN to select books excluding certain authors

💡 Why This Matters

🌍 Real World

Filtering data by multiple values is common in databases for reports, searches, and data analysis.

💼 Career

Knowing how to use IN and NOT IN helps database developers and analysts write efficient queries to get precise data.

1

Create the books table

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

MySQL

-- Write the CREATE TABLE statement for books
-- Your code here

Hint

Use CREATE TABLE books and define three columns with correct types and primary key.

2

Insert book records

Insert these exact records into the books table: (1, 'The Great Gatsby', 'F. Scott Fitzgerald'), (2, '1984', 'George Orwell'), (3, 'To Kill a Mockingbird', 'Harper Lee'), (4, 'Animal Farm', 'George Orwell'), (5, 'The Catcher in the Rye', 'J.D. Salinger').

MySQL

CREATE TABLE books (
  id INT PRIMARY KEY,
  title TEXT,
  author TEXT
);
-- Insert the 5 book records below
-- Your code here

Hint

Use a single INSERT INTO books statement with multiple value tuples.

3

Select books by specific authors using IN

Write a SQL query to select all columns from books where the author is either 'George Orwell' or 'Harper Lee' using the IN operator.

MySQL

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

INSERT INTO books (id, title, author) VALUES
(1, 'The Great Gatsby', 'F. Scott Fitzgerald'),
(2, '1984', 'George Orwell'),
(3, 'To Kill a Mockingbird', 'Harper Lee'),
(4, 'Animal Farm', 'George Orwell'),
(5, 'The Catcher in the Rye', 'J.D. Salinger');

-- Select books where author is 'George Orwell' or 'Harper Lee' using IN
-- Your code here

Hint

Use WHERE author IN ('George Orwell', 'Harper Lee') to filter authors.

4

Select books excluding specific authors using NOT IN

Write a SQL query to select all columns from books where the author is not 'F. Scott Fitzgerald' and not 'J.D. Salinger' using the NOT IN operator.

MySQL

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

INSERT INTO books (id, title, author) VALUES
(1, 'The Great Gatsby', 'F. Scott Fitzgerald'),
(2, '1984', 'George Orwell'),
(3, 'To Kill a Mockingbird', 'Harper Lee'),
(4, 'Animal Farm', 'George Orwell'),
(5, 'The Catcher in the Rye', 'J.D. Salinger');

SELECT * FROM books WHERE author IN ('George Orwell', 'Harper Lee');

-- Select books where author is NOT 'F. Scott Fitzgerald' or 'J.D. Salinger' using NOT IN
-- Your code here

Hint

Use WHERE author NOT IN ('F. Scott Fitzgerald', 'J.D. Salinger') to exclude authors.

Practice

1. What does the IN operator do in a MySQL query?

easy

A. Checks if a value is greater than all values in a list

B. Checks if a value is less than all values in a list

C. Checks if a value matches any value in a list

D. Checks if a value is equal to a single value only

Solution

1. Step 1: Understand the purpose of IN operator

   The IN operator is used to test if a value exists within a set of values.

2. Step 2: Compare with other options

   The options describing comparisons with all values (greater or less than all) are incorrect, as IN checks if a value matches any in the list. The option about equality to a single value is also wrong, since IN handles multiple values.

3. Final Answer:

   Checks if a value matches any value in a list -> Option C

4. Quick Check:

   IN operator = check value in list [OK]

Hint: IN means "is in this list"; NOT IN means "not in this list" [OK]

Common Mistakes:

• Confusing IN with equality (=) operator
• Thinking IN checks all values instead of any
• Mixing IN with greater than or less than comparisons

2. Which of the following is the correct syntax to select rows where the column status is either 'active', 'pending', or 'closed'?

easy

A. SELECT * FROM table WHERE status IN ('active', 'pending', 'closed');

B. SELECT * FROM table WHERE status = IN ('active', 'pending', 'closed');

C. SELECT * FROM table WHERE status NOT IN ('active', 'pending', 'closed');

D. SELECT * FROM table WHERE status IN 'active', 'pending', 'closed';

Solution

1. Step 1: Check correct IN syntax

   The correct syntax uses IN followed by parentheses containing a comma-separated list of values.

2. Step 2: Identify errors in other options

   SELECT * FROM table WHERE status = IN ('active', 'pending', 'closed'); has an extra '=' which is invalid. SELECT * FROM table WHERE status NOT IN ('active', 'pending', 'closed'); uses NOT IN which selects rows not matching the list. SELECT * FROM table WHERE status IN 'active', 'pending', 'closed'; misses parentheses around the list.

3. Final Answer:

   SELECT * FROM table WHERE status IN ('active', 'pending', 'closed'); -> Option A

4. Quick Check:

   Correct IN syntax uses parentheses and no '=' [OK]

Hint: IN must be followed by parentheses with values inside [OK]

Common Mistakes:

• Using '=' before IN
• Omitting parentheses around the list
• Confusing IN with NOT IN

3. Given the table employees with a column department, what will this query return?

SELECT name FROM employees WHERE department NOT IN ('HR', 'Finance');

medium

A. Names of employees in HR or Finance departments

B. Names of employees not in HR or Finance departments

C. Names of employees only in HR department

D. Syntax error due to NOT IN usage

Solution

1. Step 1: Understand NOT IN operator

   NOT IN selects rows where the column value is not in the given list.

2. Step 2: Apply to the query context

   The query returns employee names whose department is not 'HR' or 'Finance'.

3. Final Answer:

   Names of employees not in HR or Finance departments -> Option B

4. Quick Check:

   NOT IN excludes listed values [OK]

Hint: NOT IN excludes listed values from results [OK]

Common Mistakes:

• Thinking NOT IN returns only listed values
• Confusing NOT IN with IN
• Assuming syntax error with NOT IN

4. Identify the error in this query:

SELECT * FROM orders WHERE order_status NOT IN 'shipped', 'delivered';

medium

A. Missing parentheses around the list after NOT IN

B. Incorrect use of NOT IN instead of IN

C. order_status should be in quotes

D. No error, query is correct

Solution

1. Step 1: Check syntax of NOT IN usage

   NOT IN must be followed by parentheses containing the list of values.

2. Step 2: Identify missing parentheses

   The query lists values without parentheses, causing syntax error.

3. Final Answer:

   Missing parentheses around the list after NOT IN -> Option A

4. Quick Check:

   NOT IN requires parentheses around values [OK]

Hint: Always use parentheses after IN or NOT IN [OK]

Common Mistakes:

• Omitting parentheses around value list
• Using quotes incorrectly around column names
• Confusing IN and NOT IN usage

5. You want to find customers who have placed orders but exclude those from countries 'USA', 'Canada', and 'Mexico'. Which query correctly uses NOT IN to achieve this?

hard

A. SELECT customer_id FROM orders WHERE country != ('USA', 'Canada', 'Mexico');

B. SELECT customer_id FROM orders WHERE country IN ('USA', 'Canada', 'Mexico');

C. SELECT customer_id FROM orders WHERE country NOT IN 'USA', 'Canada', 'Mexico';

D. SELECT customer_id FROM orders WHERE country NOT IN ('USA', 'Canada', 'Mexico');

Solution

1. Step 1: Understand the goal

   We want customers excluding those from USA, Canada, and Mexico.

2. Step 2: Choose correct NOT IN syntax

   SELECT customer_id FROM orders WHERE country NOT IN ('USA', 'Canada', 'Mexico'); uses NOT IN with parentheses and a list, correctly excluding those countries.

3. Step 3: Identify errors in other options

   SELECT customer_id FROM orders WHERE country IN ('USA', 'Canada', 'Mexico'); includes those countries (wrong). SELECT customer_id FROM orders WHERE country NOT IN 'USA', 'Canada', 'Mexico'; misses parentheses (syntax error). SELECT customer_id FROM orders WHERE country != ('USA', 'Canada', 'Mexico'); uses != with a list, which is invalid syntax.

4. Final Answer:

   SELECT customer_id FROM orders WHERE country NOT IN ('USA', 'Canada', 'Mexico'); -> Option D

5. Quick Check:

   NOT IN with parentheses excludes listed values [OK]

Hint: Use NOT IN with parentheses to exclude multiple values [OK]

Common Mistakes:

• Using != with multiple values
• Omitting parentheses after NOT IN
• Confusing IN and NOT IN