public void RegisterFromElement(FromElement element)
        {
            _fromElements.Add(element);
            string classAlias = element.ClassAlias;

            if (classAlias != null)
            {
                // The HQL class alias refers to the class name.
                _fromElementByClassAlias.Add(classAlias, element);
            }
            // Associate the table alias with the element.
            string tableAlias = element.TableAlias;

            if (tableAlias != null)
            {
                _fromElementByTableAlias[tableAlias] = element;
            }

            if (element.IsEntityJoin())
            {
                _entityJoinFromElements.Add((EntityJoinFromElement)element);
            }
        }