user: Question: What episode premier received 0.680 million viewers?
Columns: ['#', 'Title', 'Original airdate', 'Timeslot', 'Viewers (millions)', 'Nightly rank', 'Weekly rank']
Types: ['real', 'text', 'text', 'text', 'text', 'real', 'real']
Sample row: [1.0, '"Ambushed"', '30 May 2011', 'Monday 8:30 pm – 9:30 pm', '0.805', 17.0, 47.0]
SQL:

assistant: SELECT "Original airdate" FROM "Table" WHERE "Viewers (millions)" = '0.680';