Multi Column Combo box in C Sharp

public object DataSource { get; set; }
private BindingSource bindingSource1 = new BindingSource();

       private static DataTable GetData(string sqlCommand)
   {
       string connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=school;Persist Security Info=True;";

       SqlConnection northwindConnection = new SqlConnection(connectionString);

       SqlCommand command = new SqlCommand(sqlCommand, northwindConnection);
       SqlDataAdapter adapter = new SqlDataAdapter();
       adapter.SelectCommand = command;

       DataTable table = new DataTable();
       table.Locale = System.Globalization.CultureInfo.InvariantCulture;
       adapter.Fill(table);

       return table;
   }


private void frm_book_Load(object sender, EventArgs e)
       {
           bindingSource1.DataSource = GetData("select id,code from subject");
           comboTree1.DataSource = bindingSource1;
       }

• #education
• #multi_column_combobox_c
• #multi_column_combobox_binding
• #multi_column_combobox_html
• #multi_column_combobox_items
• #multi_column_combobox
• #multi_column_combobox_properties
• #multi_column_combobox_readonly
• #multi_column_combobox_text
• #multi_column_combobox_vbnet
• #multi_column_combo_box
• #multi_column_combo_box_2021
• #multi_column_combo_box_access
• #multi_column_combo_box_keys
• #multi_column_combo_box_selection
• #multi_column_combo_box_youtube
• #multi_column_combobox_default_value