Table: joankrug_tennis
Columns: date
tournament
surface
opponent_in_the_final
score

Question: Which tournament had Lubomira Bacheva as the opponent in the final?
SQL: SELECT "tournament" FROM joankrug_tennis WHERE "opponent_in_the_final" = 'lubomira bacheva'

Question: Who was the opponent in the final on 5 July 1992?
SQL: SELECT "opponent_in_the_final" FROM joankrug_tennis WHERE "date" = '5 july 1992'

Question: What is the date of the tournament where Kyoko Nagatsuka was the opponent in the final?
SQL: SELECT "date" FROM joankrug_tennis WHERE "opponent_in_the_final" = 'kyoko nagatsuka'

Question: What is the surface at the tournament of Vaihingen?
SQL: SELECT "surface" FROM joankrug_tennis WHERE "tournament" = 'vaihingen'

Question: What was the surface of the tournament where Anna Benzon was the opponent in the final?
SQL: SELECT "surface" FROM joankrug_tennis WHERE "opponent_in_the_final" = 'anna benzon'