Can you help with milk expression process?

[CornerLeafe]

Friends, I have two separate tables in my MySQL database, each with the same user_id field. I can retrieve data from both tables, but what I need is to fetch the user_nick from the user table. When I write my query, I can retrieve the ids from the product table. How can I retrieve the user nick from the user table using that id? To illustrate with an image, we have two different tables where the user ids are the same. I want to fetch the user nick from the user table by combining these two tables.