How many films did a customer named Francis Sikes rent?
'Francis Sikes' is a full name of a customer; full name refers to first_name, last_name;
SELECT COUNT(T1.customer_id) FROM customer AS T1 INNER JOIN rental AS T2 ON T1.customer_id = T2.customer_id WHERE T1.first_name = 'FRANCIS' AND T1.last_name = 'SIKES'