roster.py

import json
import sqlite3

conn = sqlite3.connect('rosterdb.sqlite')
cur = conn.cursor()

# Do some setup
cur.executescript('''
DROP TABLE IF EXISTS User;
DROP TABLE IF EXISTS Member;
DROP TABLE IF EXISTS Course;

CREATE TABLE User (
    id     INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
    name   TEXT UNIQUE
);

CREATE TABLE Course (
    id     INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
    title  TEXT UNIQUE
);

CREATE TABLE Member (
    user_id     INTEGER,
    course_id   INTEGER,
    role        INTEGER,
    PRIMARY KEY (user_id, course_id)
)
''')

fname = input('Enter file name: - ')
if len(fname) < 1:
    fname = 'roster_data.json'

# [
#   [ "Charley", "si110", 1 ],
#   [ "Mea", "si110", 0 ],

str_data = open(fname).read()
json_data = json.loads(str_data)
#print(json_data)

num_students = 0
num_instructors = 0
for entry in json_data:

    name = entry[0]
    title = entry[1]
    role = entry[2]
    
    print()
    print('Name:',name)
    print('Course:',title)
    if role == 0:
        print('Role: Student')
        num_students += 1
    else:
        print('Role: Instructor')
        num_instructors += 1

    cur.execute('''INSERT OR IGNORE INTO User (name)
        VALUES ( ? )''', ( name, ) )
    cur.execute('SELECT id FROM User WHERE name = ? ', (name, ))
    user_id = cur.fetchone()[0]

    cur.execute('''INSERT OR IGNORE INTO Course (title)
        VALUES ( ? )''', ( title, ) )
    cur.execute('SELECT id FROM Course WHERE title = ? ', (title, ))
    course_id = cur.fetchone()[0]

    cur.execute('''INSERT OR REPLACE INTO Member
        (user_id, course_id,role) VALUES ( ?, ?,? )''',
        ( user_id, course_id,role) )

    conn.commit()
    
print('Total number of students:',num_students)
print('Total number of instructors:',num_instructors)

print()
print('Database Query below this line:')
#sql queries
sql_query_1 = ('''
    SELECT User.name,Course.title, Member.role FROM 
    User JOIN Member JOIN Course 
    ON User.id = Member.user_id AND Member.course_id = Course.id
    ORDER BY User.name DESC, Course.title DESC, Member.role DESC LIMIT 2;''')

sql_query_2 = ('''
    SELECT 'XYZZY' || hex(User.name || Course.title || Member.role)
    AS X FROM User JOIN Member JOIN Course 
    ON User.id = Member.user_id AND Member.course_id = Course.id
    ORDER BY X LIMIT 1;
''')
#query 1 loop
for entry in cur.execute(sql_query_1):
    print(entry[0],entry[1],entry[2])

#query 2 loop
for entry in cur.execute(sql_query_2):
    print(entry[0],type(entry))

cur.close