问题是由TextBox数据绑定引起的.

The problem is caused by TextBox databindings.

pcno.DataBindings.Add("Text", _pcno, "pcno");
pcname.DataBindings.Add("Text", _pcno, "pcname");

在这种形式下，当您在文本框中编辑值时，数据源将更新.

In that form DataSource is updated when you edit values in text boxes.

您可以考虑将这些行更改为:

You might consider changing those lines to:

pcno.DataBindings.Add("Text", _pcno, "pcno", false, DataSourceUpdateMode.Never);
pcname.DataBindings.Add("Text", _pcno, "pcname", false, DataSourceUpdateMode.Never);