user: Question: Who directed the episode with production code 28?
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '"Oliver Buys a Farm"', 'Ralph Levy', 'Jay Sommers', 'September15,1965', 1.0]
SQL:

assistant: SELECT "Directed by" FROM "Table" WHERE "Production code" = 28.0;