user: Question: How many episodes did David Jackson write and direct?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [46.0, 1.0, '"Like You Like an Arsonist"', 'Greg Prange', 'Mark Schwahn', 'October5,2005', '2T6151', '3.46']
SQL:

assistant: SELECT COUNT("Written by") FROM "Table" WHERE "Directed by" = 'David Jackson';