/// <summary>
/// Add selectable into the selection of the select which referred by the ref column.
/// If the ref column has a RefTo ref column, this function will also recursively add
/// the selectable to RefTo ref columns
/// </summary>
public static void AddToReferedSelect(
this IDbRefColumn refCol, IDbObjectFactory factory, string colName, Type colType, string alias = null)
{
refCol.AddToReferedSelect(factory, colName, factory.BuildType(colType), alias);
}