当按照书名查询时，系统提示没有该索引:no index with 'bookname' field.何故

Question

unit Unit4;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls, ExtCtrls, Grids, DBGrids, DB;type
  TForm4 = class(TForm)
    PageControl1: TPageControl;
    TabSheet1: TTabSheet;
    TabSheet2: TTabSheet;
    Label1: TLabel;
    Edit1: TEdit;
    Button1: TButton;
    Label2: TLabel;
    Edit2: TEdit;
    Button2: TButton;
    DBGrid2: TDBGrid;
    Panel1: TPanel;
    Label3: TLabel;
    CheckBox1: TCheckBox;
    RadioGroup1: TRadioGroup;
    Label4: TLabel;
    Edit3: TEdit;
    Edit4: TEdit;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    DBGrid1: TDBGrid;
    procedure Button5Click(Sender: TObject);
    procedure TabSheet1Show(Sender: TObject);
    procedure TabSheet2Show(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form4: TForm4;implementationuses Unit8;{$R *.dfm}
procedure TForm4.Button5Click(Sender: TObject);
begin
form4.close;
end;
procedure TForm4.TabSheet1Show(Sender: TObject);
begin {设置书名为索引字段}
   datamodule8.booktable.indexfieldnames:='bookname';
end;procedure TForm4.TabSheet2Show(Sender: TObject);
begin  {设置作者名为索引字段}
    datamodule8.booktable.indexfieldnames:='author';
end;procedure TForm4.Button2Click(Sender: TObject);
begin{根据作者名关键字查询}
  datamodule8.booktable.open;
  datamodule8.booktable.FindNearest([edit2.text]);
end;procedure TForm4.FormCreate(Sender: TObject);
beginend;
 {根据书名关键字查询}
procedure TForm4.Button1Click(Sender: TObject);
begin
  datamodule8.booktable.open;
  datamodule8.booktable.FindNearest([edit1.text])
end;end.

Answer 1

datamodule8.booktable.loate('字段名',edit1.text,[]);

Answer 2

还是不行，系统还是提示‘no index for field 'bookname''

Answer 3

我已经建立了索引，主索引是‘bookno','bookname'是second index .

Answer 4

书名为何要建立second index?书名不是可以有重的吗?把这个去掉就行了.

Answer 5

其实,如果按照你的结果完全只用一个主键索引用可以达到目的,另外,不建议你用那个书名查询方式,最好用SQL语句来完成.