最全面的DBGrid点击标题实现排序

 最全面的DBGrid标题排序实现方法：

procedure TSrv_SJSetForm.DBGridEh1TitleClick(Column: TColumnEh);
var s,cFieldName:string;
 i:integer;
 DataSet:TDataSet;
 procedure setTitle;
 var ii:integer;
     cStr:string;
     c:TColumnEh;
 begin
   for ii:=0 to TDBGridEh(Column.Grid).Columns.Count-1 do
   begin
     c:=TDBGridEh(Column.Grid).Columns[ii];
     cStr:=c.Title.Caption;
     if (pos('▲',cStr)=1) or (pos('▼',cStr)=1) then
      begin
      Delete(cStr,1,2);
      c.Title.Caption:=cStr;
      end;
   end;
 end;
begin
  //setTitle;
  DataSet:=Column.Grid.DataSource.DataSet;
  if Column.Field.FieldKind=fkLookup then
  begin
   cFieldName:=Column.Field.KeyFields;
   Exit;
  end
  else if Column.Field.FieldKind=fkCalculated then
  begin
   cFieldName:=Column.Field.KeyFields;
   Exit;
  end
  else
   cFieldName:=Column.FieldName;
  setTitle;
  //=================================AdoDataSet=====================
  if DataSet is TCustomADODataSet then begin
   s:=TCustomADODataSet(DataSet).Sort;
   if s='' then begin
     s:=cFieldName;
     Column.Title.Caption:='▲'+Column.Title.Caption;
   end
   else begin
     if Pos(cFieldName,s)<>0 then begin
       i:=Pos('DESC',s);
       if i<=0 then begin
         s:=s+' DESC';
         Column.Title.Caption:='▼'+Column.Title.Caption;
       end
       else begin
         Column.Title.Caption:='▲'+Column.Title.Caption;
         Delete(s,i,4);
       end;
     end
     else begin
       s:=cFieldName;
       Column.Title.Caption:='▲'+Column.Title.Caption;
     end;
   end;
   TCustomADODataSet(DataSet).Sort:=s;
  end
  //============================Clientdataset==========================
  else if DataSet is TClientDataSet then begin
   if TClientDataSet(DataSet).indexfieldnames<>'' then
   begin
     i:=TClientDataSet(DataSet).IndexDefs.IndexOf('i'+Column.FieldName);
     if i=-1 then
     begin
       with TClientDataSet(DataSet).IndexDefs.AddIndexDef do
       begin
         Name:='i'+cFieldName;//Column.FieldName;
         Fields:=cFieldName;//Column.FieldName;
         DescFields:=cFieldName;//Column.FieldName;
       end;
     end;
     TClientDataSet(DataSet).IndexFieldNames:='';
     TClientDataSet(DataSet).IndexName:='i'+cFieldName;//Column.FieldName;
     Column.Title.Caption:='▼'+Column.Title.Caption;
   end
   else
   begin
     TClientDataSet(DataSet).IndexName:='';
     TClientDataSet(DataSet).IndexFieldNames:=cFieldName;//Column.Fieldname;
     Column.Title.Caption:='▲'+Column.Title.Caption;
   end;
  end;
end;