数据库不会使用 MySQL 和 Python 自动更新

I'm having some trouble updating a row in a MySQL database. Here is the code I'm trying to run:

import MySQLdb

conn=MySQLdb.connect(host="localhost", user="root", passwd="pass", db="dbname")
cursor=conn.cursor()

cursor.execute("UPDATE compinfo SET Co_num=4 WHERE ID=100")
cursor.execute("SELECT Co_num FROM compinfo WHERE ID=100")
results = cursor.fetchall()

for row in results:
    print row[0]

print "Number of rows updated: %d" % cursor.rowcount

cursor.close()
conn.close()

我运行这个程序时得到的输出是: