user: Question: What type of surface was played at the tournament in Berlin?
Columns: ['Tournament', 'Surface', 'Week', 'Winner', 'Finalist', 'Semifinalists']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Boca Raton', 'Hard', 'March 2', 'Steffi Graf 3–6, 6–2, 6–0', 'Conchita Martínez', 'Mary Joe Fernandez Amanda Coetzer']
SQL:

assistant: SELECT "Surface" FROM "Table" WHERE "Tournament" = 'Berlin';