user: Question: What episode number had a cable ranking of 8?
Columns: ['Episode no.', 'Airdate', 'Viewers', 'BBC Three weekly ranking', 'Cable rank']
Types: ['real', 'text', 'real', 'text', 'text']
Sample row: [1.0, '25 March 2010', 862000.0, '3', '13']
SQL:

assistant: SELECT "Episode no." FROM "Table" WHERE "Cable rank" = '8';