This application will read roster data in JSON format, parse the file, and then produce an SQLite database that contains a User, Course, and Member table and populate the tables from the data file.
This code is incomplete as I need to modify the program to store the role column in the Member table to complete the problem. And I cannot understand how to do it.
import json
import sqlite3
conn = sqlite3.connect('rosterdb.sqlite')
cur = conn.cursor()
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 = raw_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)
for entry in json_data:
name = entry[0];
title = entry[1];
print name, title
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) VALUES ( ?, ? )''',
( user_id, course_id ) )
conn.commit()
Once the necessary changes are made to the program and it has been run successfully reading the given JSON data, run the following SQL command:
SELECT 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
Find the first row in the resulting record set and enter the long string that looks like 53656C696E613333.
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