Where is the post featured image link stored in the WordPress database?

Question

Where is the featured image link stored in the WordPress Database? I searched in the wp_postmeta table but I cannot find out the exact post_id and

Answer 1

Even if rnevius answer seemed correct, the result returned some images with this kind of URL : http://www.example.com/?attachment_id=48 which was not working in my case.

Tested on Wordpress 4.9.3 :

Another solution is to use _wp_attached_file instead :

wp_postmeta

Search for value _thumbnail_id in meta_key

meta_id   | post_id   | meta_key            | meta_value
200       | 4         | _thumbnail_id       | 48

wp_postmeta

Again in wp_postmeta, search for value _wp_attached_file in meta_key where post_id is matching the meta_value find in previous query

meta_id   | post_id   | meta_key            | meta_value
1020      | 48        | _wp_attached_file   | 2018/09/picture.jpg

Query :

SELECT wp.ID, wpm2.meta_value
FROM wp_posts wp
    INNER JOIN wp_postmeta wpm
        ON (wp.ID = wpm.post_id AND wpm.meta_key = '_thumbnail_id')
    INNER JOIN wp_postmeta wpm2
        ON (wpm.meta_value = wpm2.post_id AND wpm2.meta_key = '_wp_attached_file')