inquire from him/inquire him

[Aamir Tariq]

When we ask someone about something.

I think I should inquire from John if he is coming over for dinner or not.
I think I should inquire John if he is coming over for dinner or not.

Regards
Aamir the Global Citizen

 

[bhaisahab]

The first one is grammatical but unnatural. The second one is wrong.
Just say "I think I should ask John if he is coming over for dinner".