You can filter by NULL in Eloquent, but if you're filtering the collection further - filter by empty string, there's no "null" in that field anymore.

What if you’re working with non-Laravel database and your timestamp columns are named differently? Maybe, you have create_time and update_time. Luckily, you can specify them in the model, too

If you have DB column which you want to be set only once and never updated again, you can set that restriction on Eloquent Model, with a mutator