Table: table_name
Columns: year_location
mens_singles
womens_singles
mens_doubles
womens_doubles

Question: Who is listed under mens singles when womens has wang nan zhang yining?
SQL: SELECT "mens_singles" FROM table_name 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 table_name 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 table_name WHERE "year_location" = '1998 Doha'

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