user: Question: When 4.5 is the rating (18-49) what is the air date?
Columns: ['Episode', 'First Air Date', 'Rating (18–49)', 'Share (18–49)', 'Viewers (millions)', 'Rank (timeslot)']
Types: ['real', 'text', 'text', 'real', 'text', 'text']
Sample row: [1.0, 'January 3, 2011', '2.9', 7.0, '9.04', 'N/A']
SQL:

assistant: SELECT "First Air Date" FROM "Table" WHERE "Rating (18–49)" = '4.5';