Table: tennis_tournament_results_3
Columns: location
year
champion
runner_up
score

Question: What year weas John McEnroe the champion?
SQL: SELECT AVG("year") FROM tennis_tournament_results_3 WHERE "champion" = 'john mcenroe'

Question: Who was the runner-up, when the champion was Björn Borg after 1978?
SQL: SELECT "runner_up" FROM tennis_tournament_results_3 WHERE "champion" = 'björn borg' AND "year" > 1978

Question: Who was the champion earlier than 1978 when the runner-up was Jimmy Connors?
SQL: SELECT "champion" FROM tennis_tournament_results_3 WHERE "runner_up" = 'jimmy connors' AND "year" < 1978