txt_documentoKeypress

form4.cs

private void txt_documento_KeyPress(object sender, KeyPressEventArgs e)
        {
            
            if (e.KeyChar == 13)
            {
                string var = txt_documento.Text.ToString();

                if (var != "" || var !=" ")
                {
                    AbrirConexion();
                    SqlCommand cdo = new SqlCommand();
                    cdo.Connection = conexion;

                    cdo.CommandText = "select Codigo,Descripcion from zf_TipoDoc where Codigo='" + var + "'";

                    SqlDataReader reader = cdo.ExecuteReader();

                    while (reader.Read())
                    {
                        //cmbbox_documento.SelectedValue = reader[0].ToString();
                        cmbbox_documento.SelectedItem = new Dato() { Codigo = reader[0].ToString(), Descripcion = reader[1].ToString() };
                    }
                    reader.Close();
                    CerrarConexion();

                }
            }
            
        }