Table: iceland_international_tennis
Columns: year
men_s_singles
women_s_singles
men_s_doubles
women_s_doubles
mixed_doubles

Question: In which women's doubles did Wang Junjie play men's singles?
SQL: SELECT "women_s_doubles" FROM iceland_international_tennis WHERE "men_s_singles" = 'wang junjie'

Question: In what mixed doubles did Niels Christian Kaldau play in men's singles?
SQL: SELECT "mixed_doubles" FROM iceland_international_tennis WHERE "men_s_singles" = 'niels christian kaldau'

Question: Which mixed doubles happened later than 2011?
SQL: SELECT "mixed_doubles" FROM iceland_international_tennis WHERE "year" > 2011