Return the average and minimum age of captains in each class.
SELECT avg(age) ,  min(age) ,  CLASS FROM captain GROUP BY CLASS
SELECT avg(age) ,  min(age) ,  CLASS FROM captain GROUP BY CLASS
[{'avg(age)': 45.0, 'min(age)': '45', 'Class': 'Armed schooner'}, {'avg(age)': 43.0, 'min(age)': '43', 'Class': 'Cutter'}, {'avg(age)': 38.0, 'min(age)': '38', 'Class': 'Frigate'}, {'avg(age)': 38.0, 'min(age)': '38', 'Class': 'Sloop-of-war'}, {'avg(age)': 51.333333333333336, 'min(age)': '40', 'Class': 'Third-rate ship of the line'}]