DISTINCT

🎬 Scenario: Finding Unique Subscription Plans#

Your manager at Netflix, Alex, is analyzing customer trends and wants to know which unique subscription plans are currently active.

Alex asks:

Can you provide a list of all the different subscription plans that exist in our database?

Your task is to query the netflix_users table and provide the requested data.

Removing Duplicates with DISTINCT#

By default, when you SELECT a column, SQL returns all records, even if some values repeat. The DISTINCT keyword removes duplicate values, ensuring that each unique value appears only once.

Syntax:

SELECT DISTINCT column_name  
FROM table_name;

Example Query: Finding Unique Subscription Plans

SELECT DISTINCT subscription_plan  
FROM netflix_users;

Expected Output:

What’s Happening?

• The DISTINCT keyword removes duplicate subscription plans from the result set.
• Instead of listing every user’s plan, we get a concise summary of all available options.

Using DISTINCT with Multiple Columns#

We can also apply DISTINCT to multiple columns, ensuring unique combinations of values are returned.

Example Query: Finding Unique Subscription Plans by Country

SELECT DISTINCT subscription_plan, country  
FROM netflix_users;

Expected Output:

What’s Happening?

• The query ensures that each combination of subscription_plan and country appears only once.

✍️ SQL Exercises#

Exercise 1: Identifying Countries with Netflix Users#

Netflix wants to identify all unique countries where users have signed up.

Filter condition:

• Retrieve a distinct list of country values from the netflix_users table.

Expected Output:

Write an SQL query to return the requested data.

Exercise 2: Finding Unique Watch History Entries#

Netflix’s data team wants to know the different combinations of users and series they have watched to understand viewer engagement. Sort the table based on the ascending order of user_id and series_id

Filter condition:

• Retrieve unique pairs of user_id and series_id from the watch_history table.

Expected Output:

Write an SQL query to return the requested data.