user: Question: Which episode number aired on 18 October 2012?
Columns: ['Episode no.', 'Airdate', 'Dave Viewers', 'Dave Rank', 'Rank (cable)', 'Dave ja vu Viewers', 'Total viewers']
Types: ['real', 'text', 'real', 'real', 'real', 'real', 'real']
Sample row: [1.0, '4 October 2012', 1978000.0, 1.0, 3.0, 113000.0, 2091000.0]
SQL:

assistant: SELECT "Episode no." FROM "Table" WHERE "Airdate" = '18 October 2012';