What is the department name of the students with lowest gpa belongs to?
SELECT T2.dept_name FROM student AS T1 JOIN department AS T2 ON T1.dept_code  =  T2.dept_code ORDER BY stu_gpa LIMIT 1
lowest gpa refers to MIN(stu_gpa); department name = dept_name; students belongs to a department refers to JOIN between student and department on dept_code;