This is basically the definition of clever-but-should-never-actually-be-used-in-production.

The explicit typecasting wasn't really necessary here.

Even though this is clearly not a recursive function, reusing the name bmi does not seem like best practices to me.

That was very helpful. Thanks for the recommendation!

I don't know anything about ip addresses, but while looking through the documentation I found the answer. So basically every network has a beginning ip address and an ending one. So given an ip address in a network, you need to generate the corresponding beginning and ending ip addresses and return the id of that original ip address when you do it. I'm probably explaining that entirely wrong, but the point is that the first_address and last_address are not necessarily elements of the table themselves. They are generated from the ip addresses that are in the table.

Wow. Just ... wow.

You might want to consider ways to keep your code DRY (look up that principle if you don't know what I'm referencing).