仅使用数据集更新数据库不会插入

Question

I have a grid view in asp.net which I am populating like this:

     sda1 = new SqlDataAdapter("select * from tran_dtls where tc='" + tcdropDown.SelectedValue + "'and doc_no='" + DocNoTxt.Text + "'", con);
     build = new SqlCommandBuilder(sda1);
     sda1.Fill(ds);                      //ds is a data set
     GridView1.DataSource = ds;
     GridView1.DataBind();

I update the grid view by passing the ds to a new data table, adding a new row in datatable then again binding the datatable to the grid:

       dt = (DataTable)ViewState["myViewState"];
              dt = ds.Tables[0];
              dr = dt.NewRow();
              dr["TC"] = Session["TC"];
              dr["sr_no"] = Session["i"].ToString(); //I have more fields but for simplicity only displaying few
              dt.Rows.Add(dr);
              dt.AcceptChanges();
              ViewState["myViewState"] = dt;

              Session["gridRow"] = dt;

Everything is smooth uptil now ,but when I try to update the database(after inserting new entries in the dataset) it doesn't work the save button code is below:

 protected void onSaveClick(object sender, EventArgs e)
    {


        dt = (DataTable)Session["gridRow"];// I am passing the data table in a session    as I am entering the new entry from a pop up window
        dt.GetChanges(DataRowState.Modified);


        sda1.Fill(dt);

        sda1.Update(dt);   
    }

Funny part is when I edit a the existing entry in dt it does edit(classic sql update) but it never insert any new entries which are added in the data table ,and it doesn't even throw a error

Answer 1

This line

dt.AcceptChanges(); 

marks all rows in the datatable as Unchanged.

When you call

dt.GetChanges(DataRowState.Modified); 

you get only the rows modified after the AcceptChanges()

Moreover, to get the rows Added to the database the correct statement will be

dt.GetChanges(DataRowState.Added); 

but, as I have said, this will return nothing due to the AcceptChanges() call.
You should remove the AcceptChanges() statement.
Also, I don't think you need to call this in the logic of the save button

sda1.Fill(dt);