How many times is the number of images containing "broccoli" than "tomato"?
images refers to IMG_ID; "broccoli" refers to OBJ_CLASS = 'broccoli'; "tomato" refers to OBJ_CLASS = 'tomato' ; How many times = divide(count(OBJ_SAMPLE_ID) when OBJ_CLASS = 'broccoli', count(OBJ_SAMPLE_ID) when OBJ_CLASS = 'tomato')
SELECT CAST(COUNT(CASE WHEN T1.OBJ_CLASS = 'broccoli' THEN T2.OBJ_SAMPLE_ID ELSE NULL END) AS REAL) / COUNT(CASE WHEN T1.OBJ_CLASS = 'tomato' THEN T2.OBJ_SAMPLE_ID ELSE NULL END) times FROM OBJ_CLASSES AS T1 INNER JOIN IMG_OBJ AS T2 ON T1.OBJ_CLASS_ID = T2.OBJ_CLASS_ID