Find and list the full name of customers who rented more family movies than Sci-Fi movies.
full name refers to first_name, last_name; 'family' AND 'Sci-Fi' are names of the category; customers who rented more family movies than Sci-Fi movies refers to count(name = 'Family') > count(name = 'Sci-Fi')
SELECT DISTINCT IIF(SUM(IIF(T5.name = 'Family', 1, 0)) - SUM(IIF(T5.name = 'Sci-Fi', 1, 0)) > 0, T1.first_name, 0) FROM customer AS T1 INNER JOIN rental AS T2 ON T1.customer_id = T2.customer_id INNER JOIN inventory AS T3 ON T2.inventory_id = T3.inventory_id INNER JOIN film_category AS T4 ON T4.film_id = T3.film_id INNER JOIN category AS T5 ON T4.category_id = T5.category_id GROUP BY T1.customer_id