MySQLdb not updating rows

[Bowen]

import md5
import string
import MySQLdb

tc = raw_input("Teacher Code: ")
p = raw_input("New Password: ")

print tc
hash = md5.new()
hash.update(p)
print p
print hash.hexdigest()
h = hash.hexdigest()

boo = raw_input("Sure you want to update password with above details? Y
or N: ")

if boo == 'y':
    db = MySQLdb.connect("copweb2", "******", "******", "*******")
    cursor = db.cursor()
    if cursor.execute("UPDATE teachers SET password = '%s' WHERE
teacher_code = '%s'" % (h, tc)):
        print "Done"
    else:
        print "Error"
else:
    print "cancelled"

cursor.close()
db.close()


This code doesn't seem to update my database, anyone any idea why? Is
it me being stupid? It doesn't kick out an error at all.