user: Question: How many directed by have 2.80 as u.s. viewers  (in millions)?
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'U.S. viewers (in millions)']
Types: ['real', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '" Pilot "', 'Mark Piznarski', 'Teleplay by: Josh Schwartz & Stephanie Savage', 'September19,2007', '3.50']
SQL:

assistant: SELECT COUNT("Directed by") FROM "Table" WHERE "U.S. viewers (in millions)" = '2.80';