返回当前的记录

nit Unit2;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Grids, DBGrids, ExtCtrls, DBCtrls, StdCtrls, ComCtrls, TabNotBk,
  DB, DBTables, ADODB;type
  TQueryForm = class(TForm)
    TabbedNotebook1: TTabbedNotebook;
    RadioGroup1: TRadioGroup;
    GroupBox1: TGroupBox;
    Edit1: TEdit;
    Button1: TButton;
    DBNavigator1: TDBNavigator;
    DBGrid1: TDBGrid;
    DBNavigator2: TDBNavigator;
    DBGrid2: TDBGrid;
    Button2: TButton;
    RadioGroup2: TRadioGroup;
    GroupBox2: TGroupBox;
    Edit2: TEdit;
    Label1: TLabel;
    DBNavigator3: TDBNavigator;
    DBGrid3: TDBGrid;
    Label2: TLabel;
    Button3: TButton;
    Edit3: TEdit;
    ADOQuery1: TADOQuery;
    DataSource1: TDataSource;
    procedure Button1Click(Sender: TObject);
    procedure RadioGroup1Click(Sender: TObject);
   // procedure Button2Click(Sender: TObject);
   // procedure Button3Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  QueryForm: TQueryForm;implementation{$R *.dfm}
uses unit7;
procedure TQueryForm.Button1Click(Sender: TObject);
var
   str:string;
begin
  with QueryDataModule do
  begin
    case RadioGroup1.ItemIndex of
    0: with studentquery do
       begin
         DBGrid1.DataSource := nil;
         close;
         str:=' select * from student ';
         str:=str+ ' where sno= '+''''+self.Edit1.Text +'''';
         studentquery.Active :=false;
         studentquery.SQL.CommaText :=str;
         studentquery.Active :=true;
         DBNavigator1.DataSource:=dsstudent ;
         dbgrid1.DataSource :=dsstudent;
       end;
    1: with TeachersQuery do
       begin
         DBGrid1.DataSource := nil ;
         close;
         str:=' select * from teacher ';
         str:=str+' where tno= '+''''+ self.Edit1.Text +'''';
         TeachersQuery.Active :=false;
         TeachersQuery.SQL.CommaText :=str;
         TeachersQuery.Active :=true;
         open;
         DBNavigator1.DataSource:= DSTeachers ;
         dbgrid1.DataSource := DSTeachers;
        // teachersquery.RecordCount ;
       end;
    2: with CourseQuery do
       begin
          DBGrid1.DataSource := nil;
          close;
          str:=' select * from Course where cno= '+''''+self.Edit1.Text +'''';
          CourseQuery.Active:=false;
          CourseQuery.SQL.CommaText :=str;
          CourseQuery.Active:=true;
          dBNavigator1.DataSource:=  DSCourse ;
          dbgrid1.DataSource :=  DSCourse;
       end;
         end;
end;
end;
procedure TQueryForm.RadioGroup1Click(Sender: TObject);//如何设置返回当前的记录就是刚查询的记录重新在一次出显,而不要当击BUTTON1就可以的.
var
  i:integer;
  booklist:tbooklist;
  book:tbook;
begin
   if  RadioGroup1.ItemIndex = 0  then
      book:=unit7.QueryDataModule.StudentQuery.GetBook
   else if
      unit7.QueryDataModule.StudentQuery.GetBook    // DBGrid1.DataSource := nil
   else if RadioGroup1.ItemIndex = 1 then
     DBGrid1.DataSource := nil
  else if RadioGroup1.ItemIndex = 2 then
     DBGrid1.DataSource := nil;end;