user: Question: What is the duration for Mike Walling as the actor?
Columns: ['Character', 'Actor', 'Duration', 'Role', 'Appearances']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['"Stupid" Brian', 'Kevin Bishop', '2001', "Janey's Boyfriend", '3']
SQL:

assistant: SELECT "Duration" FROM "Table" WHERE "Actor" = 'Mike Walling';