SQL statement to find participant count for specific tournament id?

Where in the database does the participant count for a tournament live? I see post types for tournament, matches, teams etc… but there are no data columns that hold participant counts for a tournament.

Let’s say a tournament (ID: 1) has a current participant list of 6 teams. Where does that 6 live, and what example SQL statement would you write to uncover that number?

Thank you