I want to adapt my old custom website database (composed of only one table) to Wordpress database.

All data has been correctly imported in both tables (wp_posts and wp_postmeta) with a php code that I can share if needed.

Here is a screenshot of my wp_posts table...

...and a screenshot of my wp_postmeta table (I imported only one entry to facilitate understanding).

As you can see, wp_posts/post_parent column of id 2 (referring to the featured image) is well linked to id 1 (which is the post).

But in my wordpress admin panel, I still have no linked featured image.

Is there another place where the image and the post have to be linked?