在python中使用sqlite3：是否不更新数据库？

Question

我正在编写一个用于存储密码的程序，但它似乎并未写入数据库。 当我“添加密码”时，它不会显示错误，但是当我“查找现有密码”时，我得到的只是一个空数组（即[]）。 请注意，由于我直到文件的最后才提交更改，因此我退出，重新加载，然后搜索现有密码。

在我的文件夹中，我已经有一个空文件'passwords.db'。

这是我的代码：

import sys
import sqlite3 as lite

con = lite.connect("passwords.db")
cur = con.cursor()

cur.execute("CREATE TABLE if not EXISTS passwords(site VARCHAR(50), username VARCHAR(20), password VARCHAR(20));")

print "Welcome to Passwords.py."

choice = None

while choice == None:
    print "What would you like to do?"
    print "1.) Add new password."
    print "2.) Find existing password."
    print "3.) Update existing password."
    print "4.) Quit."
    choice = raw_input("> ")

    if choice == "1":
        s = raw_input("Which website to add? ")
        name = raw_input("Username to add? ")
        passwd = raw_input("Password to add? ")

        cur.execute("INSERT INTO passwords VALUES (?,?,?)", (s,name,passwd))

        choice = None

    elif choice == "2":
        s = raw_input("Find info for which website? ")

        cur.execute("SELECT * FROM passwords WHERE site=?", (s,))

        print cur.fetchall()

        choice = None

    elif choice == "3":
        s = raw_input("Update info for which website? ")
        name = raw_input("New username? ")
        passwd = raw_input("New password? ")

        cur.execute("UPDATE passwords SET username, password WHERE site=?", (s,))

        choice = None

    elif choice == "4":
        quit()

    else:
        print "Enter 1, 2, or 3."
        choice = None

### cleaning up.

if con:
    con.commit()
    con.close()

令人反感的程序：

laura@laura-AO722:~/Desktop/passwords$ python passwords.py
Welcome to Passwords.py.
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 1
Which website to add? a
Username to add? b
Password to add? c
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 4
laura@laura-AO722:~/Desktop/passwords$ python passwords.py
Welcome to Passwords.py.
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 2
Find info for which website? a
[]

Answer 1

您的更新SQL应该看起来像这样

cur.execute("UPDATE passwords SET username=?, password=? WHERE site=?", (name, passwd, s,))

这是我得到的输出

>>> 
Welcome to Passwords.py.
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 1
Which website to add? google.com
Username to add? john
Password to add? pass
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 2
Find info for which website? google.com
[(u'google.com', u'john', u'pass')]
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 3
Update info for which website? google.com
New username? john2
New password? pass2
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
> 2
Find info for which website? google.com
[(u'google.com', u'john2', u'pass2')]
What would you like to do?
1.) Add new password.
2.) Find existing password.
3.) Update existing password.
4.) Quit.
>