CREATE TABLE student (stu_fname VARCHAR2, stu_lname VARCHAR2, stu_num VARCHAR2)
CREATE TABLE enroll (stu_num VARCHAR2, class_code VARCHAR2)
CREATE TABLE course (crs_description VARCHAR2, crs_code VARCHAR2)
CREATE TABLE CLASS (class_code VARCHAR2, crs_code VARCHAR2)

Find names of all students who took some course and the course description.
SELECT T1.stu_fname, T1.stu_lname, T4.crs_description FROM student AS T1 JOIN enroll AS T2 ON T1.stu_num = T2.stu_num JOIN CLASS AS T3 ON T2.class_code = T3.class_code JOIN course AS T4 ON T3.crs_code = T4.crs_code
SELECT "T1"."stu_fname", "T1"."stu_lname", "T4"."crs_description" FROM "student" "T1" JOIN "enroll" "T2" ON "T1"."stu_num" = "T2"."stu_num" JOIN "CLASS" "T3" ON "T2"."class_code" = "T3"."class_code" JOIN "course" "T4" ON "T3"."crs_code" = "T4"."crs_code"