一个很实用的Ehlib排序函数，适合ADO

Ehlib3.0版本以上虽然支持排序功能，但不支持带有Order By的SQL语句，而且排序很慢；我写的这个排序函数，利用ADO的sort方法，排序很快，几万条数据也是很快。该函数支持Lookup字段排序，不支持计算字段排序，因为计算字段值在内存里高速运算。排序分为：升序、降序和默认三种，支持排序图标。

procedure SortDBGridEh(Sender: TObject; ACol: Integer;
  Column: TColumnEh);
var
  FieldName, SortStr: string;
begin
  Screen.Cursor := crSQLWait;
  try
  if (Sender is TDBGridEh) and
  ((Sender as TDBGridEh).DataSource.DataSet <> nil) then
  begin
  if not ((Sender as TDBGridEh).DataSource.DataSet is TCustomADODataSet) then
  Exit;

  if not (Sender as TDBGridEh).DataSource.DataSet.Active then
  Exit;

  FieldName := Column.FieldName;
  if (Sender as TDBGridEh).DataSource.DataSet.FindField(FieldName).IsBlob then
  Exit;

  if (Sender as TDBGridEh).DataSource.DataSet.FieldByName(FieldName).FieldKind =
  fkData then
  SortStr := FieldName
  else if (Sender as TDBGridEh).DataSource.DataSet.FieldByName(FieldName).FieldKind =
  fkLookup then
  FieldName := (Sender as TDBGridEh).DataSource.DataSet.FieldByName(FieldName).KeyFields
  else
  FieldName := '';

  if (FieldName = '') or (Pos(';', FieldName) > 0) then
  Exit;
  case Column.Title.SortMarker of
  smNoneEh:
  begin
  Column.Title.SortMarker := smUpEh;
  TCustomADODataSet((Sender as TDBGridEh).DataSource.DataSet).Sort :=
  FieldName;

  end;
  smUpEh:
  begin
  Column.Title.SortMarker := smDownEh;
  TCustomADODataSet((Sender as TDBGridEh).DataSource.DataSet).Sort :=
  FieldName + ' DESC';
  end;
  smDownEh:
  begin
  Column.Title.SortMarker := smNoneEh;
  TCustomADODataSet((Sender as TDBGridEh).DataSource.DataSet).Sort := '';
  end;
  end;
  end;
  finally
  Screen.Cursor := crDefault;
  end;
end;

--程序实现如下：
--在DBGridEh的事件OnTitleBtnClick引用该函数即可：
procedure TFrmU_BasicSetup.dbgAddrCodeTitleBtnClick(Sender: TObject;
  ACol: Integer; Column: TColumnEh);
begin
  SortDBGridEh(Sender, ACol, Column);
end;
--为了保证表格的每一列都能点击触发排序，你需要将你需要排序的列属性 
-- Title->TitleButton设置为True。