组合框“所选文本已更改”事件未触发

Question

This is my code. After adding data through DataSource , The SelectedIndexChanged event is not firing.

try
{
    comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
    comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;

    //comboBox1.Items.Clear();

    comboBox1.ResetText();

    Cn.Open();
    SqlCommand Cd = new SqlCommand("Select Distinct Mobile From Client_Details Where Branch = '" + label2.Text + "'", Cn);
    SqlDataReader da = Cd.ExecuteReader();
    DataTable dt = new DataTable();

    dt.Columns.Add("Mobile", typeof(string));
    dt.Load(da);
    comboBox1.DisplayMember = "Mobile";
    comboBox1.DataSource = dt;
    comboBox1.SelectedItem = "<Select>";
}
catch
{

}
finally
{
    Cn.Close();
    Clear();
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
    //Label CBSL = new Label();
    //string CBSL = this.comboBox1.SelectedItem.ToString();

    if (comboBox9.Text == "Client")
    {
        Update_Read_Client();
    }
    else if (comboBox9.Text == "Customer")
    {
        Update_Read();
    }
}

1. It selects the first value again and again.
2. I had tried DropDownStye = DropDownList., But it become dormant. No values is added.
3. Any help to resolve my problem.

Answer 1

I'm not sure if you have "< Select >" item saved in your database. Also, when using DataTable it's easier to fill it using SqlDataAdapter . You should also use parameters instead of string concat when you're writing your query like this and using keyword closes your connection automatically when you're done using it. I'd write it like this probably:

comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems;

using (SqlConnection con = new SqlConnection(connectionString))
{
    SqlCommand cmd = con.CreateCommand();
    cmd.CommandType = CommandType.Text;
    cmd.CommandText = @"SELECT DISTINCT Mobile
                        FROM Client_Details
                        WHERE Branch = @Branch";
    cmd.Parameters.AddWithValue("@Branch", label2.Text);

    try
    {
        var dt = new DataTable();
        dt.Columns.Add("Mobile", typeof(string));

        SqlDataAdapter da = new SqlDataAdapter(cmd);
        da.Fill(dt);

        DataRow row = dt.NewRow();
        row["Mobile"] = "<Select>";                    
        dt.Rows.InsertAt(row, 0);

        comboBox1.DisplayMember = "Mobile";
        comboBox1.DataSource = dt;
        comboBox1.SelectedItem = "<Select>";
    }
    catch
    {
        throw;
    }
}