ch15assignment2.py

import sqlite3

conn = sqlite3.connect('py4edata.sqlite')
cur = conn.cursor()

cur.execute("DROP TABLE IF EXISTS Counts")

cur.execute("CREATE TABLE Counts (org TEXT, count INTEGER)")

fname = input('Enter file name: ')
if (len(fname) < 1): fname = 'mbox.txt'
fh = open(fname)
for line in fh:
    if not line.startswith('From: '): continue
    pieces = line.split()
    email = pieces[1]
    domain_name = email.split("@")[1]
    cur.execute('SELECT count FROM Counts WHERE org = ? ', (domain_name,))
    row = cur.fetchone()
    if row is None:
        cur.execute('''INSERT INTO Counts (org, count)
                VALUES (?, 1)''', (domain_name,))
    else:
        cur.execute('UPDATE Counts SET count = count + 1 WHERE org = ?',
                    (domain_name,))
conn.commit()

# https://www.sqlite.org/lang_select.html
sqlstr = 'SELECT org, count FROM Counts ORDER BY count DESC LIMIT 10'

for row in cur.execute(sqlstr):
    print(str(row[0]), row[1])

cur.close()