datagridview event causing datagridview to no fill up properly

Question

Both of these functions are working fine, one should fill up datagrid with data, the other, should be triggered when i select a row from the first datagrid. But for some reason the second function is causing datagrid to fill just one row of data.

private void fillDataGrid(DataGridView dg, string query) {
            OracleCommand cmd = new OracleCommand(query);
            cmd.CommandType = CommandType.Text;
            cmd.Connection = conn;
            OracleDataAdapter oda = new OracleDataAdapter(cmd);
            DataTable dt = new DataTable();
            try {
                cmd.ExecuteNonQuery();
                oda.Fill(dt);
                **dg.DataSource = dt;**
            }
            catch(Exception e) {
                MessageBox.Show(e.ToString());
            }
        }

This function is called when i load the form, and it is working fine on its own. But when the next function is causing some kind of problem and i don't know why.

private void dataGridView1_SelectionChanged_1(object sender, EventArgs e)
        {
            String s = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
            String upit = "select dn.* from detaljinarudzbe dn, narudzba n where dn.nid = n.nid and n.jmbg = " + s + "";
            fillDataGrid(dataGridView2, upit);
        }

It is working fine, but i get just one row in first datagridview. And expection says

system.argument out of range exception:must be non negative and less than the size of collection

Caused by the ** line in first method. I don't get why is the event causing this problem. when i use the second function on a button it is working fine.

Answer 1

You can try (I using SQL Server) : attention check SelectedRows[0] by SelectedRows.Count

private void fillDataGrid(DataGridView dg, string query) {
        SqlCommand cmd = new SqlCommand(query);
        cmd.CommandType = CommandType.Text;
        cmd.Connection = conn;

        SqlDataAdapter oda = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        try {
            conn.Open();
            cmd.ExecuteNonQuery();
            oda.Fill(dt);
            conn.Close();
            dg.DataSource = dt;
        }
        catch(Exception e) {
            MessageBox.Show(e.ToString());
        }
        finally
        {

        }
    }
private void dataGridView1_SelectionChanged(object sender, EventArgs e)
    {
        if(dataGridView1.SelectedRows.Count > 0)
        {
            String s = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
            String upit = "Select * from CARD_NO where CT_ID = " + s + "";
            fillDataGrid(dataGridView2, upit);
        }

    }
private void Form1_Load(object sender, EventArgs e)
    {
        fillDataGrid(dataGridView1, "Select * from CARD_TYPE");
    }