再问DbGrid按列标题排序问题

Question

下列事件过程,点击列标题后能排序,颜色和▼\▲能够切换,但是,点击另一列后,原来那一列的▼或▲符号不会消失.我的要求是,点击另一列后原来的那一列只显示列标题,不在显示▼或▲符号,请问怎么处理?
procedure TForm1.DBGrid3TitleClick(Column: TColumn);
var i:integer;
begin
 if adoquery2.Sort = Column.FieldName then  //AdoQCX为MyDBGrid绑定的Tadoquery
   begin
     For i:=0 to dbgrid3.Columns.Count-1 do
       dbgrid3.Columns[i].Title.RestoreDefaults;
     adoquery2.sort := Column.FieldName + ' DESC';
     Column.Title.Font.Color:=clPurple;    //用紫色表示 逆序
     dbgrid3.Canvas.Refresh ;
     Column.Title.Caption:=dbgrid3.SelectedField.FieldName + '▼' ;
   end
 else begin
   For i:=0 to dbgrid3.Columns.Count-1 do
     dbgrid3.Columns[i].Title.RestoreDefaults;
   adoquery2.Sort := Column.FieldName;
   Column.Title.Font.Color:=clBlue;    //用蓝色表示正序字段
   dbgrid3.Canvas.Refresh ;
   column.Title.Caption:=dbgrid3.SelectedField.FieldName + '▲' ;
   end;
end;

Answer 1

点击后循环各COULMN判断是不是当前列如何!不是就把题头改下!

Answer 2

怎么置空?是这样吗?通不过
column.Title.Caption:='';

Answer 3

我为了与广大DELPHI爱好者共同讨论，建立了一个群，欢迎大家加入！
群号是：5245338

Answer 4

procedure TForm1.DBGridTitleClick(Column: TColumn);
var s,cFieldName:string;
    i:integer;
    DataSet:TDataSet;
    procedure setTitle;
    var ii:integer;
        cStr:string;
        c:TColumn;
    begin
      for ii:=0 to TDBGrid(Column.Grid).Columns.Count-1 do
      begin 
        c:=TDBGrid(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
    cFieldName:=Column.Field.KeyFields
  else if Column.Field.FieldKind=fkCalculated then 
    cFieldName:=Column.Field.KeyFields
  else
    cFieldName:=Column.FieldName;
  if DataSet is TCustomADODataSet then begin
    s:=TCustomADODataSet(DataSet).Sort;
    if s='' then begin
      s:=cFieldName;
      Column.Title.Caption:='▲'+Column.Field.DisplayName; 
    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.Field.DisplayName; 
        end 
        else begin
          Column.Title.Caption:='▲'+Column.Field.DisplayName; 
          Delete(s,i,4);
        end; 
      end 
      else begin
        s:=cFieldName; 
        Column.Title.Caption:='▲'+Column.Field.DisplayName;
      end; 
    end; 
    TCustomADODataSet(DataSet).Sort:=s;
  end 
  else if DataSet is TClientDataSet then begin
//    TClientDataSet(DataSet).IndexFieldNames:=Column.FieldName; 
    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'+Column.FieldName; 
          Fields:=Column.FieldName;
          DescFields:=Column.FieldName; 
        end; 
      end;
      TClientDataSet(DataSet).IndexFieldNames:=''; 
      TClientDataSet(DataSet).IndexName:='i'+Column.FieldName;
      Column.Title.Caption:='▼'+Column.Field.DisplayName; 
    end 
    else
    begin 
      TClientDataSet(DataSet).IndexName:='';
      TClientDataSet(DataSet).IndexFieldNames:=column.fieldname; 
      Column.Title.Caption:='▲'+Column.Field.DisplayName; 
    end;
  end;
end;