user: Question: How many episodes directed by David Carson?
Columns: ['No. in series', 'No. in season', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [63.0, 1.0, '"The Unsterile Cuckoo"', 'Rob Thompson', 'David E. Kelley', 'November2,1989', '7D01']
SQL:

assistant: SELECT COUNT("No. in season") FROM "Table" WHERE "Directed by" = 'David Carson';