使用this.TableManager.UpdateAll更新数据库，但发生重复键错误

Question

我尝试使用this.TableManager.UpdateAll更新数据库。添加的第一个客户端很好，但是当我想添加一个新客户端时，我得到了重复的密钥错误。这是代码：

    //using a try command so if there is an exception, it will display it
        try
        {
            //check if there are any changes prevents someone pressing save twice and you may get duplicate entries in database
            if (this.allensCroftDataSet.HasChanges())
            {
                //It will then check if a row has been added:
                if ((this.TableManager.UpdateAll(this.allensCroftDataSet) > 0))
                {
                    //And it will then display a message box saying “saved”.
                    MessageBox.Show("Saved.");
                }
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }