CREATE TABLE captain (Captain_ID NUMBER, Name CLOB, Ship_ID NUMBER, age CLOB, Class CLOB, Rank CLOB)
CREATE TABLE Ship (Ship_ID NUMBER, Name CLOB, Type CLOB, Built_Year FLOAT, Class CLOB, Flag CLOB)

What is the total number of captains in each rank and class? Let class as X-axis, and categorize by rank with a stacked bar chart.
SELECT Class, COUNT(Class) FROM captain GROUP BY Rank, Class
SELECT "Class", COUNT("Class") FROM "captain" GROUP BY "Rank", "Class"