Why doesn't DISTINCT work?

Question

MySQL

I have a sql query

SELECT * FROM video_category INNER JOIN category ON category.id = video_category.category_id INNER JOIN video ON video.id = video_category.video_id WHERE video_category.category_id = :id ORDER BY video_category.video_id DESC

The request displays data, but for some reason they are repeated

Changed the request to

SELECT DISTINCT * FROM video_category INNER JOIN category ON category.id = video_category.category_id INNER JOIN video ON video.id = video_category.video_id WHERE video_category.category_id = :id ORDER BY video_category.video_id DESC

Those. added DISTINCT, it should remove duplicate entries, but for some reason this does not happen, what's the problem?

Answer 1

DISTINCT is distributed to all columns specified in SELECT, and at you id does not repeat. Use GROUP BY on the columns you need.