Give the student's last name that gave the highest student satisfaction for the course "Intro to Database 2".
student's last name refers to l_name; satisfaction refers to sat; highest satisfaction refers to MAX(sat);
SELECT T1.l_name FROM student AS T1 INNER JOIN registration AS T2 ON T1.student_id = T2.student_id INNER JOIN course AS T3 ON T2.course_id = T3.course_id WHERE T3.name = 'Intro to Database 2' ORDER BY T2.sat DESC LIMIT 1