Question

i have tried to to load the data to text box, while selecting the drop down list, i was created a class for retrieval and called it in drop down list selected index changed. But i cant get the answer what i want. If i have called the class in Button click event it has worked properly. So please correct me. What i made a mistake. This is what my code:

public void so()
    {
        con.Open();
        string s2;
        s2 = "select Source from tbl_component where Componetcode='" + Mcodeddl.SelectedItem.Text + "'";
        SqlCommand c2 = new SqlCommand(s2, con);
        SqlDataReader d2;
        d2 = c2.ExecuteReader();
        while (d2.Read())
        {
            TextBox1.Text = d2["Source"].ToString().Trim(); 

        }
        d2.Close();
        con.Close();
    }

//i have called the so class here

 protected void Mcodeddl_SelectedIndexChanged(object sender, EventArgs e)
    {
        so();   
    }

Answer 1

You should set a breakpoint inside your Mcodeddl_SelectedIndexChanged method to see if the event is triggered, also make sure include AutoPostBack="true" in your dropdownlist definition