I upgraded a site and have many missing featured images. I 've tried a few plugins that are supposed to set the first uploaded image to be "featured" if the featured image wasn't manually set, but so far, I have not had any luck with using a plugin to do so.
My question is: Could anyone tell me if there is a query I can run on the backend of my wordpress database using mysql directly that would allow me to see how many of my existing posts are missing the featured image setting? This way I could determine whether or not I can just go in and do this manually, or if I need to come up with a different option. Thank you!