C # Do select and display in a combobox

Following this table layout in a SQL Server database a>:

1-With DataTable : / p>

public DataTable GetUF()
{
    DataTable dataUf = new DataTable("UF");
    using (SqlConnection Connection = new SqlConnection(@"Data Source=.\SqlExpress;Initial Catalog=Db;Persist Security Info=True;User ID=sa;Password=senha"))
    using (SqlCommand Command = new SqlCommand("SELECT UFID, SIGLA FROM UF ORDER BY SIGLA", Connection))
    {
        Connection.Open();
        dataUf.Load(Command.ExecuteReader());
    }
    return dataUf;
}

Loading Data from the DataTable into the ComboBox CmbUF

CmbUF.DropDownStyle = ComboBoxStyle.DropDownList;
CmbUF.DataSource = GetUF();
CmbUF.ValueMember = "UFID";
CmbUF.DisplayMember = "SIGLA";
CmbUF.Update();

2 - With Classe UF and IEnumerable :

Create a class that represents the data that served as a template for loading the ComboBox.

public class UF
{
        public int UFID { get; set; }
        public String SIGLA { get; set; }
}

Loading data into IEnumerable<UF>

public IEnumerable<UF> GetUF()
{
    using (SqlConnection Connection = new SqlConnection(@"Data Source=.\SqlExpress;Initial Catalog=Db;Persist Security Info=True;User ID=sa;Password=senha"))
    using (SqlCommand Command = new SqlCommand("SELECT UFID, SIGLA FROM UF ORDER BY SIGLA", Connection))
    {
        Connection.Open();
        using (SqlDataReader Reader = Command.ExecuteReader())
        {
            if (Reader.HasRows)
            {
                while (Reader.Read())
                {
                    yield return new UF()
                    {
                        UFID = Reader.GetInt32(0),
                        SIGLA = Reader.GetString(1)
                    };
                }
            }
        }
    }            
}

Loading the data from IEnumerable<UF> to the ComboBox CmbUF

CmbUF.DropDownStyle = ComboBoxStyle.DropDownList;
CmbUF.DataSource = GetUF().ToArray();
CmbUF.ValueMember = "UFID";
CmbUF.DisplayMember = "SIGLA";
CmbUF.Update();

Note: Note that GetUF() should now call ToArray() , because the DataSource needs an IList or #

Quick explanation of what was used in ComboBox

CmbUF.DataSource = "FONTE DE DADOS (DATATABLE, DATASET, ILIST, etc)";
CmbUF.ValueMember = "NOME DO CAMPO QUE REPRESENTA A IDENTIFICAÇÃO DE CADA ITEM DO COMBOBOX";
CmbUF.DisplayMember = "TEXTO QUE SERÁ MOSTRADO NO COMBOBOX";            

var c = CmbUF.SelectedValue; //RECUPERANDO O VALOR DA UFID