40. Channels with No Videos in the Dataset

Solution ↗

Medium

Tables: channels, videos

+-------------------------+-------------+
| Column Name             | Type        |
+-------------------------+-------------+
| channel_id              | varchar     |
| channel_name            | varchar     |
| subscriber_count        | bigint      |
| view_count              | bigint      |
+-------------------------+-------------+
channels contains one row per YouTube channel.
channel_id is the primary key for this table.

+-------------------------+-------------+
| Column Name             | Type        |
+-------------------------+-------------+
| video_id                | varchar     |
| channel_id              | varchar     |
| title                   | varchar     |
| published_at            | datetime    |
+-------------------------+-------------+
videos contains one row per video.
video_id is the primary key for this table.
channel_id is a foreign key referencing channels.channel_id.

Write a SQL query to find channels that do not have any matching records in the videos table.

Hint

Tip: LEFT JOIN plus NULL filter reveals missing matches.

Input:

channels table:
+------------+------------------+------------------+------------+
| channel_id | channel_name     | subscriber_count | view_count |
+------------+------------------+------------------+------------+
| C101       | Alpha Tech       | 2500000          | 92000000   |
| C102       | Data With Mira   | 1800000          | 71000000   |
| C103       | SQL Zone         | 950000           | 40000000   |
+------------+------------------+------------------+------------+

videos table:
+----------+------------+-------------------+---------------------+
| video_id | channel_id | title             | published_at        |
+----------+------------+-------------------+---------------------+
| V1       | C101       | Python Basics     | 2024-01-11 10:00:00 |
| V2       | C101       | Tableau Project   | 2024-03-05 10:00:00 |
| V3       | C102       | SQL Joins         | 2024-04-10 09:00:00 |
| V4       | C102       | Window Functions  | 2024-05-01 09:00:00 |
| V5       | C103       | Intro to MySQL    | 2024-02-07 11:30:00 |
+----------+------------+-------------------+---------------------+

Output:

Output:
+------------+--------------+
| channel_id | channel_name |
+------------+--------------+
|            |              |
+------------+--------------+

Explanation:

If every channel has videos in the dataset, the result can be empty.