CREATE TABLE invoices (customer_id VARCHAR(255)); CREATE TABLE customers (id VARCHAR(255), first_name VARCHAR(255), last_name VARCHAR(255))
How many orders does Lucas Mancini has?
    
SQL: SELECT COUNT(*) FROM customers AS T1 JOIN invoices AS T2 ON T1.id = T2.customer_id WHERE T1.first_name = "Lucas" AND T1.last_name = "Mancini"