当您创建新的datatable时，它是空的 - 即没有行。这就是为什么在索引 0 找不到行。您应该手动创建和添加行。

When you create new datatable, it is empty - i.e. there is no rows. That's why you can't find row at index 0. You should create and add rows manually.

使用 DataTable.NewRow 方法来创建与您的datatable相同的列（即相同的模式）的新行：

Use DataTable.NewRow method to create new row with same columns (i.e. same schema) as your datatable:

DataRow row = obj_dt_grdvw.NewRow(); // create new row
row["_Pur_Product_Id"] ="12"; // set field values
row["Product_pur_Name"] ="milk";
obj_dt_grdvw.Rows.Add(row); // add this new row to table rows