procedure TForm1.DBGrid1TitleClick(Column: TColumn);
var
 temp, title: string;
begin
 temp := Column.FieldName;
 qusp.Close;
 if Column.Index <> lastcolumn then
 begin
   if (Pos('↑', DBGrid1.Columns[LastColumn].Title.Caption) > 0) or (Pos('↓', DBGrid1.Columns[LastColumn].Title.Caption) > 0) then
     DBGrid1.Columns[LastColumn].Title.Caption := Copy(DBGrid1.Columns[LastColumn].Title.Caption, 3, Length(DBGrid1.Columns[LastColumn].Title.Caption) - 2);
   qusp.Sql[icount] := 'order by ' + temp + ' asc';
   DBGrid1.Columns[Column.Index].Title.Caption := '↑' + DBGrid1.Columns[Column.Index].Title.Caption;
   lastcolumn := column.Index;
 end
 else
 begin
   LastColumn := Column.Index;
   title := DBGrid1.Columns[LastColumn].Title.Caption;
   if Pos('↑', title) > 0 then
   begin
     qusp.Sql[icount] := 'order by ' + temp + ' desc';
     Delete(title, 1, 2);
     DBGrid1.Columns[LastColumn].Title.Caption := '↓' + title;
   end
   else if Pos('↓', title) > 0 then
   begin
     qusp.Sql[icount] := 'order by ' + temp + ' asc';
     Delete(title, 1, 2);
     DBGrid1.Columns[LastColumn].Title.Caption := '↑' + title;
   end
   else
   begin
     qusp.Sql[icount] := 'order by ' + temp + ' asc';
     DBGrid1.Columns[LastColumn].Title.Caption := '↑' + title;
   end;
 end;
 qusp.Open;
end;

（出处：www.delphibbs.com）

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