How many products shipped on 19/11/1994 were ordered on 21/09/1994?
shipped on 19/11/1994 refers to l_shipdate = '1994-11-19'; ordered on 21/09/1994 refers to o_orderdate = '1994-09-21'
SELECT COUNT(T2.l_partkey) FROM orders AS T1 INNER JOIN lineitem AS T2 ON T1.o_orderkey = T2.l_orderkey WHERE T1.o_orderdate = '1994-09-21' AND T2.l_shipdate = '1994-11-19'