Find the name of the instructors who taught C Programming course before.
create table teaches (id varchar, course_id varchar, PRIMARY KEY (id)); create table course (course_id varchar, title varchar, PRIMARY KEY (course_id)); create table instructor (name varchar, id varchar, PRIMARY KEY (name))
select t1.name from instructor as t1 join teaches as t2 on t1.id = t2.id join course as t3 on t2.course_id = t3.course_id where t3.title = 'c programming'