Selenium and Database testing

I am totally new to the web application and automation testing. I am learning selenium from youtube videos and developing frameworks. while looking into the videos most of them cover only testing the Application as such.

I found very few videos which state about interacting with the database and verifying them. I just wanted to know how will this be in real time projects? In real time projects will they automating scenarios like configuring something in the UI, then validating it in the database, coming back to the UI and continuing the UI flow or will it be simply only verifying the UI.

I want to know more about how to do database testing.

Any info here will be of great help