Table: tennis_stadiums
Columns: rank
stadium
capacity
city
country
tournament_hosted

Question: What country has grandstand stadium as the stadium?
SQL: SELECT "country" FROM tennis_stadiums WHERE "stadium" = 'grandstand stadium'

Question: What is the average capacity that has switzerland as the country?
SQL: SELECT AVG("capacity") FROM tennis_stadiums WHERE "country" = 'switzerland'

Question: What is the average capacity that has rod laver arena as the stadium?
SQL: SELECT AVG("capacity") FROM tennis_stadiums WHERE "stadium" = 'rod laver arena'