Close database connection after write to the db

How to use the “DB Connection Close” node properly to close the db connection after done with writing to the DB? I searched on related post: How to use database connection closer node - #2 by ipazin
But I can’t figure out how to use flow variable to the “DB Connection Close” node to close the DB when last node operation is done(in my case the db writer node).

There is no need to assign variable. Just copy what you see on example.