Table: tennis_aces
Columns: aces
player
opponent
event
sets

Question: How many Sets did Gary Muller have?
SQL: SELECT COUNT("sets") FROM tennis_aces WHERE "player" = 'gary muller'

Question: What Player in 2005 Wimbledon had less than 5 Sets?
SQL: SELECT "player" FROM tennis_aces WHERE "sets" < 5 AND "event" = '2005 wimbledon'

Question: At the 2001 Davis Cup, what Opponent had less than 50 Aces?
SQL: SELECT "opponent" FROM tennis_aces WHERE "aces" < 50 AND "event" = '2001 davis cup'