CREATE TABLE table_28051 ("Episode no." FLOAT, "Airdate" CLOB, "Dave Viewers" FLOAT, "Dave Rank" FLOAT, "Rank  ( cable ) " FLOAT, "Dave ja vu Viewers" FLOAT, "Total viewers" FLOAT)

Which episode number aired on 18 october 2012?
SELECT MIN("Episode no.") FROM table_28051 WHERE "Airdate" = '18 October 2012'
SELECT MIN("Episode no.") FROM "table_28051" WHERE "Airdate" = '18 October 2012'