user: Question: Who won the men's singles in 1999?
Columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1988.0, 'Kim Brodersen', 'Katrin Schmidt', 'Markus Keck Robert Neumann', 'Katrin Schmidt Nicole Baldewein', 'Markus Keck Katrin Schmidt']
SQL:

assistant: SELECT "Men's singles" FROM "Table" WHERE "Year" = 1999.0;