Update

public  bool Update(string task_No,string use_Flag)
        {
            ComDataContext context = new ComDataContext(ComDataContext.ConneStr);
            try
            {

            // 如果是修改单个字段建议先查出来再修改制定字段，比查出来再删除->再保存要少操作一次数据库,无需删除这一步
                TaskInfoModel modelNew = context.TaskInfoModel.Single(b => b.task_No == task_No);
                modelNew.Use_Flag  =use_Flag ;
                context.SubmitChanges();
                return true;
            }
            catch (Exception ex)
            {
              

            }

        }