sqlite3.OperationalError: table users has no column named username

Question

您好，我不知道该问题的解决方案。我在 google 上搜索但没有得到任何答案。我是数据库的新手。所以这可能是个愚蠢的问题 :)。

class Users:
    def __init__(self, tablename="users", userId="userId", password="password", username="username"):
        self.__tablename = tablename
        self.__userId = userId
        self.__password = password
        self.__username = username
        conn = sqlite3.connect('test.db')
        print("open database successfully")
        str = "CREATE TABLE IF NOT EXISTS " +  tablename + "(" + self.__userId + " " + " INTEGER PRIMARY KEY AUTOINCREMENT ,"
        str += " " + self.__password +  "TEXT   NOT NULL ,"
        str += " " + self.__username +  "TEXT   NOT NULL )"
        conn.execute(str)
        print("Table created successfully")
        conn.commit()
        conn.close()
    def insert_user(self, username, password):

        conn = sqlite3.connect('test.db')
        str_insert = "INSERT INTO " + self.__tablename + " (" + self.__username +"," + self.__password + ") VALUES (" +  "'" +username + "'" + "," + "'" +password +"'" +");"
        print(str_insert)
        conn.execute(str_insert)
        conn.commit()
        conn.close()
        print("Record created successfully")


u = Users()
u.insert_user("yonatan@gmail.com", "123456")

Answer 1

问题在这里：

str = "CREATE TABLE IF NOT EXISTS " +  tablename + "(" + self.__userId + " " + " INTEGER PRIMARY KEY AUTOINCREMENT ,"
str += " " + self.__password +  "TEXT   NOT NULL ,"
str += " " + self.__username +  "TEXT   NOT NULL )"

实际上，连接 "username" 和 "TEXT NOT NULL" 将得到 "usernameTEXT NOT NULL"，而 "username" 和 "TEXT"

之间没有 space

如果您执行以下查询，您可以看到这一点：

conn.execute("SELECT * from sqlite_master").fetchall()

这给你：

[
    ('table', 'users', 'users', 2, 'CREATE TABLE users(userId  INTEGER PRIMARY KEY AUTOINCREMENT , passwordTEXT   NOT NULL , usernameTEXT   NOT NULL )'), 
    ('table', 'sqlite_sequence', 'sqlite_sequence', 3, 'CREATE TABLE sqlite_sequence(name,seq)')
]

这显然是一团糟。

当您使用 sqlite3 时，一个好的做法是使用以下语法，这将避免您犯很多 space 错误：

conn.execute(
    f"CREATE TABLE IF NOT EXISTS {tablename}"
    f"({self.__userId} INTEGER PRIMARY KEY AUTOINCREMENT,"
    f"{self.__password} TEXT NOT NULL, {self.__username} TEXT NOT NULL)"
)

sqlite3.OperationalError: table users has no column named username

sqlite3.OperationalError: table users has no column named username

python

database

sqlite