How many orders in total are made by customers in Germany?
orders refer to o_orderkey; Germany is the name of the nation which refers to n_name = 'GERMANY';
SELECT COUNT(T2.c_custkey) FROM nation AS T1 INNER JOIN customer AS T2 ON T1.n_nationkey = T2.c_nationkey INNER JOIN orders AS T3 ON T2.c_custkey = T3.o_custkey WHERE T1.n_name = 'GERMANY'