CREATE TABLE "table1_28138035_27" (
  "year_location" text,
  "mens_singles" text,
  "womens_singles" text,
  "mens_doubles" text,
  "womens_doubles" text
);

Question: Who is listed under mens singles when womens has wang nan zhang yining?
SQL: SELECT "mens_singles" FROM "table1_28138035_27" WHERE "womens_doubles"='Wang Nan Zhang Yining';

Question: How many womens singles entries are there when womens doubles is li xiaodan wen jia?
SQL: SELECT COUNT("womens_singles") FROM "table1_28138035_27" WHERE "womens_doubles"='Li Xiaodan Wen Jia';

Question: Who is listed under womens singles when year location is 1998 doha?
SQL: SELECT "womens_singles" FROM "table1_28138035_27" WHERE "year_location"='1998 Doha';

Question: Who is listed under mens singles when the year location is 2009 doha?
SQL: SELECT "mens_singles" FROM "table1_28138035_27" WHERE "year_location"='2009 Doha';