Table: whoseline_episodes_2
Columns: date
episode
performer_1
performer_2
performer_3
performer_4

Question: What is the average episode number where jimmy mulville was the 4th performer?
SQL: SELECT AVG("episode") FROM whoseline_episodes_2 WHERE "performer_4" = 'jimmy mulville'

Question: What is the total number of episodes where hugh laurie was the 3rd performer?
SQL: SELECT COUNT("episode") FROM whoseline_episodes_2 WHERE "performer_3" = 'hugh laurie'

Question: What is the lowest episode number where john bird was the 4th performer?
SQL: SELECT MIN("episode") FROM whoseline_episodes_2 WHERE "performer_4" = 'john bird'

Question: Who was the 3rd performer when Rory Bremner was the 4th performer?
SQL: SELECT "performer_3" FROM whoseline_episodes_2 WHERE "performer_4" = 'rory bremner'