python连接msyql查询是否存在元素

import tkinter as tk
from tkinter import messagebox
import pymysql

# 创建数据库连接
conn = pymysql.connect(host='localhost',user='root',
                             password='pananjun',
                             db='cus',
                             charset='utf8')

# 创建游标对象
cursor = conn.cursor()


class 查找元素(tk.Tk):
    def __init__(self):
        super().__init__()

        self.title('查找元素')
        self.geometry('600x400')

        # 创建框架
        frame = tk.Frame(self)
        frame.pack(padx=20, pady=20, fill=tk.BOTH, expand=True)

        # 输入要查找的元素
        self.var = tk.StringVar()
        entry = tk.Entry(frame, textvariable=self.var)
        entry.grid(row=0, column=0, padx=10, pady=10)

        # 查找按钮
        lookup_btn = tk.Button(frame, text='查找', command=self.lookup)
        lookup_btn.grid(row=0, column=1, pad