System.InvalidOperationException:This.NpgsqlTransaction has completed;it is no longer usable. at Npgsql.NpgsqlTransaction.CheckCompleted() in ...

　關於報此異常，原因是事務不能循環提交，一個方法中事務只能提交一次。

System.InvalidOperationException:This.NpgsqlTransaction has completed;it is no longer usable. at Npgsql.NpgsqlTransaction.CheckCompleted() in ...

  正確使用方法

 using (var pay = _postgreDbContext.Database.BeginTransaction())
            {
                try
                {
                    billItem.review_remark = "通過";
                    foreach (var item in Settlement)
                    {
                        item.status = 2;
                    }
                    _postgreDbContext.SaveChanges();
                   pay.Commit();//注意放到循環外面

                }
                catch (Exception ex)
                {
                    throw ex;
                }
            }