Error adding from database to dropdownlist

Question

I have a panel that is visible only when the Edit button from GridView is clicked.

In that panel is a form with a DropDownList and a TextBox where you can write a number and add it to a ListBox .

After all the numbers wanted are added to the ListBox when I click the button Finalize is adding to the database the data. In Gridview I have the name concatenate from database , because I have Lastname and Firstname separately.

To be more easy I chose to add from database in DropDownList when I click on Edit button with the specific ID.

When Edit button is clicked this error is showing:

Operation is not valid due to the current state of the object.

In the line where I add in DropDownList . I verified the names of my database, of my table , all and is correct. I even tried only with firstname , not concatenate and it does the same error. I don't know what is wrong. I hope you can help me. This is the code where the error appears.

protected void btnEditSO_Click(object sender, EventArgs e)
{
    panelSO.Visible = true;
    btnFinalizeSO.Text = " Update ";

    Button but = (Button)sender;
    GridViewRow grid = (GridViewRow)but.NamingContainer;

    string select_sql_SOddl = "SELECT ID, (LASTNAMER | | ' ' | | FIRSTNAMER ) AS REFERENTNAME FROM REFERENT_SHIPPING WHERE ID=" + grid.Cells[14].Text;

    using (OracleConnection con = new OracleConnection(ConfigurationManager.ConnectionStrings["DBCS"].ToString()))
    {
        con.Open();

        OracleCommand cmd1 = new OracleCommand(select_sql_SOddl, con);

        OracleDataReader dr1 = cmd1.ExecuteReader();

        while (dr1.Read())
        {
            ddlReferentShip.Items.Add(dr[0].ToString());
         // ddlReferentShip.Items.Add(dr["REFERENTNAME"].ToString());
         //   ddlReferentShip.DataSource = dr1;
        //    ddlReferentShip.DataTextField = dr1["REFERENTNAME"].ToString();
        //    ddlReferentShip.DataValueField = dr1["ID"].ToString();               
        //    ddlReferentShip.DataBind();
        }

    }

}

Answer 1

You are checking dr1.Read()

and reading dr[0].Tostring()

Also try to clear the list before adding the data. Then the index should be 1 if you need to show the name

it should be

 while (dr1.Read())
        {
            ddlReferentShip.Items.Add(dr1[1].ToString());

        }

I guess ID is numeric in query you are passing as .Text

try this

string select_sql_SOddl = "SELECT ID, (LASTNAMER | | ' ' | | FIRSTNAMER ) AS REFERENTNAME 
FROM REFERENT_SHIPPING WHERE ID=" + Convert.ToInt32(grid.Cells[14].Text);

also all ways try to use parameterized query to avoide SQL INJECTION

Answer 2

Why you set ddl item from dr when you have dr1 as datareader.

Maybe you can try this:

protected void btnEditSO_Click(object sender, EventArgs e)
{
    panelSO.Visible = true;
    btnFinalizeSO.Text = " Update ";

    Button but = (Button)sender;
    GridViewRow grid = (GridViewRow)but.NamingContainer;

    string select_sql_SOddl = "SELECT ID, (LASTNAMER | | ' ' | | FIRSTNAMER ) AS REFERENTNAME FROM REFERENT_SHIPPING WHERE ID=" + grid.Cells[14].Text;


    using (OracleConnection con = new OracleConnection(ConfigurationManager.ConnectionStrings["DBCS"].ToString()))
    {
        con.Open();
        OracleCommand cmd = new OracleCommand(select_sql_SO, con);
        OracleCommand cmd1 = new OracleCommand(select_sql_SOddl, con);
        OracleDataReader dr = cmd.ExecuteReader();
        OracleDataReader dr1 = cmd1.ExecuteReader();

        int i=0;
        while (dr1.Read())
        {
            ddlReferentShip.Items.Add(dr1[1].ToString());
            i++;
         // ddlReferentShip.Items.Add(dr["REFERENTNAME"].ToString());
         //   ddlReferentShip.DataSource = dr1;
        //    ddlReferentShip.DataTextField = dr1["REFERENTNAME"].ToString();
        //    ddlReferentShip.DataValueField = dr1["ID"].ToString();               
        //    ddlReferentShip.DataBind();
        }

    }

}