CREATE TABLE Course (CID VARCHAR, CName VARCHAR, Credits INT, Instructor INT, Days VARCHAR, Hours VARCHAR, DNO INT)
CREATE TABLE Student (StuID INT, LName VARCHAR, Fname VARCHAR, Age INT, Sex VARCHAR, Major INT, Advisor INT, city_code VARCHAR)
CREATE TABLE Faculty (FacID INT, Lname VARCHAR, Fname VARCHAR, Rank VARCHAR, Sex VARCHAR, Phone INT, Room VARCHAR, Building VARCHAR)
CREATE TABLE Enrolled_in (StuID INT, CID VARCHAR, Grade VARCHAR)
CREATE TABLE Department (DNO INT, Division VARCHAR, DName VARCHAR, Room VARCHAR, Building VARCHAR, DPhone INT)
CREATE TABLE Member_of (FacID INT, DNO INT, Appt_Type VARCHAR)
CREATE TABLE Minor_in (StuID INT, DNO INT)
CREATE TABLE Gradeconversion (lettergrade VARCHAR, gradepoint FLOAT)

A bar chart shows the distribution of Days and the average of Instructor , and group by attribute Days.
SELECT Days, AVG(Instructor) FROM Course GROUP BY Days ORDER BY Credits
SELECT "Days", AVG("Instructor") FROM "Course" GROUP BY "Days" ORDER BY "Credits" NULLS FIRST