From the section table, return the distinct combinations of semester and year in which sections were offered. Sort by year ascending , then by semester ascending .
Database schema
− + Fit classroom building varchar(15) room_number varchar(7) capacity numeric(4,0) department dept_name varchar(20) building varchar(15) budget numeric(12,2) time_slot time_slot_id varchar(4) day varchar(1) start_time time end_time time course course_id varchar(8) title varchar(50) dept_name varchar(20) credits numeric(2,0) instructor ID varchar(5) name varchar(20) dept_name varchar(20) salary numeric(8,2) student ID varchar(5) name varchar(20) dept_name varchar(20) tot_cred numeric(3,0) section course_id varchar(8) sec_id varchar(8) semester varchar(6) year numeric(4,0) building varchar(15) room_number varchar(7) time_slot_id varchar(4) advisor s_id varchar(5) i_id varchar(5) prereq course_id varchar(8) prereq_id varchar(8) teaches ID varchar(5) course_id varchar(8) sec_id varchar(8) semester varchar(6) year numeric(4,0) takes ID varchar(5) course_id varchar(8) sec_id varchar(8) semester varchar(6) year numeric(4,0) grade varchar(2) primary key foreign keyarrow points to the referenced column drag to pan