I created a new db and successfully created all tables.
And I clicked /install/upgrade.php , it shows
"This upgrade has been completed. Please remove the entire install directory"

I haven't pointed my old db and run any altertable scripts , why it shows upgrade completed ??

What's the correct steps to upgrade from 7.2.2 to 7.3.1 ?

English is not my native language. I try my best to express my thought precisely. I hope you understand what I mean. If any misunderstanding results from culture gaps, I apologize first.