DBGrid单击标题自动排序

procedure TForm1.DBGrid1TitleClick(Column: TColumn);
var
s,cFieldName:string;
i:integer;
DataSet:TDataSet;
begin
Try DataSet:=Column.Grid.DataSource.DataSet;
if not DataSet.Active then exit;
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;
end else
begin
if Pos(cFieldName,s)<>0 then
begin
i:=Pos('DESC',s);
if i<=0 then
begin
s:=s+' DESC';
end else
begin
Delete(s,i,4);
end;
end else
begin
s:=cFieldName;
end;
end;
TCustomADODataSet(DataSet).Sort:=s;
end 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'+Column.FieldName;
Fields:=Column.FieldName;
DescFields:=Column.FieldName;
end;
end;
TClientDataSet(DataSet).IndexFieldNames:='';
TClientDataSet(DataSet).IndexName:='i'+Column.FieldName;
end else
begin
TClientDataSet(DataSet).IndexName:='';
TClientDataSet(DataSet).IndexFieldNames:=column.fieldname;
end;
end;
Except
End;
end;