Table: riggs_matches
Columns: outcome
year
championship
surface
opponent_in_the_final
score_in_the_final

Question: Which Outcome has a Championship of us championships, and a Score in the final of 5–7, 6–1, 6–3, 6–3?
SQL: SELECT "outcome" FROM riggs_matches WHERE "championship" = 'us championships' AND "score_in_the_final" = '5–7, 6–1, 6–3, 6–3'

Question: Which Outcome has a Year larger than 1939, and an Opponent in the final of frank kovacs?
SQL: SELECT "outcome" FROM riggs_matches WHERE "year" > 1939 AND "opponent_in_the_final" = 'frank kovacs'

Question: Which Surface has an Opponent in the final of don mcneill, and a Year of 1940?
SQL: SELECT "surface" FROM riggs_matches WHERE "opponent_in_the_final" = 'don mcneill' AND "year" = 1940

Question: How many years have an Opponent in the final of welby van horn?
SQL: SELECT SUM("year") FROM riggs_matches WHERE "opponent_in_the_final" = 'welby van horn'