static string dataConnection = ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
        static IDbConnection connection = new MySqlConnection(dataConnection);
        public static string GetCode()
        {
            using (connection)
            {
　　　　　　　　　　//查询
                string  code = connection.Query<string>($"SELECT orignal_code FROM `pack_code_oc` ").FirstOrDefault();
　　　　　　　　　　//删除
                connection.Execute($"delete   FROM `pack_code_oc` where orignal_code=‘{code}‘");
                return code;
            }
        }