【python处理MySQL】查询邮箱总是报错

MySQL表内共有3个数据

账号 密码 邮箱

查询到有输入邮箱地址就返回Flase，否则返回True

一直try失败！求大佬指教

数据库表代码如下

    try:
        create_sqil="create table uid_info (uid varchar(18),password varchar(18),mail varchar(30));"
        cur.execute(create_sqil)
    except Exception as e:
        print('创建数据表失败！')
    else:
        print('创建数据表成功！')
    cur.close()

代码如下

def data_regist_mail(email):
    sql = "SELECT * FROM uid_info \
                   WHERE mail = %s" % (email)
    try:
        cur.execute(sql)
        data = cur.fetchall()
        print(data)
        if data != None:
            print('email已返回True')
            return 'True'
        else:
            for row in data:
                Uid = row[0]
                Password = row[1]
                email = row[2]
                print("Uid=%s,Password=%s,mail=%s" % (Uid, Password, email))
                return 'UID_FLASE'
    except:
        print("Regist_mail:Error: unable to fecth data")
    cur.close()

使用形参传递邮箱地址，传递的是string类型，使用tkinter输入！

报错：Regist_mail:Error: unable to fecth data