自我没有传递给Python中的类方法[关闭]

Question

我正在尝试以下 python 代码：

import sqlite3
class database:

    def __init__(self):
        self.conn = sqlite3.connect("warehousedb.db")
        self.cursor = self.conn.cursor()
        self.cursor.execute(
            "CREATE TABLE IF NOT EXISTS `admin` (admin_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, username TEXT, password TEXT)")
        self.cursor.execute(
            "CREATE TABLE IF NOT EXISTS `product` (product_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, product_name TEXT, product_qty TEXT, product_price TEXT)")
        self.cursor.execute("SELECT * FROM `admin` WHERE `username` = 'admin' AND `password` = 'admin'")

        if self.cursor.fetchone() is None:
            self.cursor.execute("INSERT INTO `admin` (username, password) VALUES('admin', 'admin')")
            self.conn.commit()


    def __del__(self):
        self.cursor.close()
        self.conn.close()

    def Execute_SQL(self, sql):
        self.cursor.execute(sql)
        self.conn.commit()

    def Get_SQL(self, sql):
        self.cursor.execute(sql)
        return self.cursor.fetchall()

    def Get_SQL_One_Rec(self, sql):
        self.cursor.execute(sql)
        return self.cursor.fetchone()

然后在尝试这段代码时：

db = database()    
st = "SELECT * FROM `admin` WHERE `username` = '" + USERNAME.get() + "' AND `password` = '" + PASSWORD.get() + "'"
rec = db.Get_SQL_One_Rec(st)

我收到以下错误：

rec = db.Get_SQL_One_Rec(st) TypeError：Get_SQL_One_Rec() 缺少 1 个必需的位置参数：'sql'

我可以从 Python 文档中看到 Self 对象是自动传递的，那么为什么会出现此错误？

Answer 1

您提供的代码有效，请参阅此链接：

https://repl.it/@zlim00/self-is-not-passed-to-the-class-method-in-python

与您的代码相比的唯一区别是此 sqllite 数据库位于内存中而不是文件中。因此，如果代码对您不起作用，则错误在于您尚未提交的部分代码。

代码（如果链接被删除）：

import sqlite3
class database:
    def __init__(self):
        self.conn = sqlite3.connect(":memory:")
        self.cursor = self.conn.cursor()
        self.cursor.execute(
            "CREATE TABLE IF NOT EXISTS `admin` (admin_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, username TEXT, password TEXT)")
        self.cursor.execute(
            "CREATE TABLE IF NOT EXISTS `product` (product_id INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, product_name TEXT, product_qty TEXT, product_price TEXT)")
        self.cursor.execute("SELECT * FROM `admin` WHERE `username` = 'admin' AND `password` = 'admin'")

        if self.cursor.fetchone() is None:
            self.cursor.execute("INSERT INTO `admin` (username, password) VALUES('admin', 'admin')")
            self.conn.commit()


    def __del__(self):
        self.cursor.close()
        self.conn.close()

    def Execute_SQL(self, sql):
        self.cursor.execute(sql)
        self.conn.commit()

    def Get_SQL(self, sql):
        self.cursor.execute(sql)
        return self.cursor.fetchall()

    def Get_SQL_One_Rec(self, sql):
        self.cursor.execute(sql)
        return self.cursor.fetchone()

if __name__ == '__main__':
    db = database()    
    st = "SELECT * FROM `admin` WHERE `username` = '" + 'admin' + "' AND `password` = '" + 'admin' + "'"
    rec = db.Get_SQL_One_Rec(st)
    print(rec)