user: Question: Who won the mixed doubles in the years that the men's doubles has No competition?
Columns: ['Year', "Men's singles", "Women's singles", "Men's doubles", "Women's doubles", 'Mixed doubles']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['1975', 'Victor Yusim', 'No competition', 'Victor Yusim Michael Schneidman', 'No competition', 'No competition']
SQL:

assistant: SELECT "Mixed doubles" FROM "Table" WHERE "Men's doubles" = 'No competition';