What is the longest duration for a bike trip starting on a day with a fog in 2013?
longest duration refers to MAX(duration); starting on a day with a fog refers to start_date where events = 'fog'; in 2013 refers to date LIKE '%2013';
SELECT MAX(T1.duration) FROM trip AS T1 INNER JOIN weather AS T2 ON T2.zip_code = T1.zip_code WHERE T2.date LIKE '%2013%' AND T2.events = 'Fog' AND T2.zip_code = 94107