Table: football_club_stats_2
Columns: club
location
manager
stadium
capacity
team_captain

Question: Who's captain of the team whose stadium has a capacity of 17800 people?
SQL: SELECT "team_captain" FROM football_club_stats_2 WHERE "capacity" = 17800

Question: How many different team captains does the club Sliven 2000 have?
SQL: SELECT COUNT("team_captain") FROM football_club_stats_2 WHERE "club" = 'Sliven 2000'

Question: Who's the captain of the team whose stadium is Gradski Stadion?
SQL: SELECT "team_captain" FROM football_club_stats_2 WHERE "stadium" = 'Gradski Stadion'

Question: What stadium has capacity for 13800?
SQL: SELECT "stadium" FROM football_club_stats_2 WHERE "capacity" = 13800

Question: How many people can attend games in the stadium of the team whose captain is Vasil Vasilev?
SQL: SELECT "capacity" FROM football_club_stats_2 WHERE "team_captain" = 'Vasil Vasilev'