python为mysql上的CRUD操作创建类

Question

当我尝试调用将数据推送到DB的方法时，我遇到以下错误。

文件“ /root/sw/conda/yes/lib/python3.6/site-packages/mysql/connector/cursor.py”，行482，在执行中     如果不是self._connection： ReferenceError：弱引用对象不再存在

#!/usr/bin/python

导入mysql.connector sql类：

dbc = ("127.0.0.1","root","1234","users")

def __init__(self):
    db = mysql.connector.connect(
host="127.0.0.1",
user="root",
passwd="",
database="ml"
)
    self.cursor = db.cursor()
    print(self.cursor)




def query2(self,sql):
    print("testttttt",sql)
    print(self.cursor)
    self.cursor.execute(sql)
    return self.cursor.fetchall()

def commit(self):
    self.cursor.commit()


def fetchall(self):
    return self.cursor.fetchall()


def fetchone(self):
    return self.cursor.fetchone()

obj=  sql()
obj.query2('SELECT * FROM calculatedsd')
print(obj.fetchall())