user: Question: Who wrote the episode where the original air date is July20,2007?
Columns: ['Series no.', 'No. in season', 'Title', 'Written by', 'Directed by', 'Original air date', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [78.0, 1.0, '"Mr. Monk and His Biggest Fan"', 'Andy Breckman', 'Randall Zisk', 'July13,2007', 'N/A']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Original air date" = 'July20,2007';