CREATE TABLE department (dept_name VARCHAR, dept_code VARCHAR)
CREATE TABLE course (dept_code VARCHAR, crs_code VARCHAR, crs_credit INT)
CREATE TABLE CLASS (crs_code VARCHAR)

Find the name of the department that offers the largest number of credits of all classes.
SELECT T3.dept_name FROM course AS T1 JOIN CLASS AS T2 ON T1.crs_code = T2.crs_code JOIN department AS T3 ON T1.dept_code = T3.dept_code GROUP BY T1.dept_code ORDER BY SUM(T1.crs_credit) DESC LIMIT 1
SELECT "T3"."dept_name" FROM "course" AS "T1" JOIN "CLASS" AS "T2" ON "T1"."crs_code" = "T2"."crs_code" JOIN "department" AS "T3" ON "T1"."dept_code" = "T3"."dept_code" GROUP BY "T1"."dept_code" ORDER BY SUM("T1"."crs_credit") DESC NULLS LAST LIMIT 1