//选择 country 表中的所有字段SELECT * FROM country{虽然 SQL 并不区分大小写, 但应习惯把关键字大写}

unit Unit1;interfaceuses  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,  Dialogs, StdCtrls, ExtCtrls, Grids, DBGrids, DB, ADODB;type  TForm1 = class(TForm)    Panel1: TPanel;    Button1: TButton;    Button2: TButton;    DBGrid1: TDBGrid;    DataSource1: TDataSource;    ADODataSet1: TADODataSet;    procedure FormCreate(Sender: TObject);    procedure Button1Click(Sender: TObject);    procedure Button2Click(Sender: TObject);  end;var  Form1: TForm1;implementation{$R *.dfm}{查看数据库 dbdemos.mdb 中的 country 表}procedure TForm1.Button1Click(Sender: TObject);begin  ADODataSet1.Close;  ADODataSet1.CommandText := 'SELECT * FROM country';  ADODataSet1.Open;end;{查看数据库 dbdemos.mdb 中的 customer 表}procedure TForm1.Button2Click(Sender: TObject);begin  with ADODataSet1 do begin    Close;    CommandText := 'SELECT * FROM customer';    Open;  end;end;{控件关联、连接数据库: dbdemos.mdb}procedure TForm1.FormCreate(Sender: TObject);var  mdbFile: string;begin  {获取 CodeGear 共享安装的数据文件: dbdemos.mdb 的路径}  mdbFile := GetEnvironmentVariable('COMMONPROGRAMFILES'); {C:\Program Files\Common Files}  mdbFile := mdbFile + '\CodeGear Shared\Data\dbdemos.mdb';  ADODataSet1.ConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=' +    mdbFile + ';Persist Security Info=False';  DBGrid1.DataSource := DataSource1;  DataSource1.DataSet := ADODataSet1;end;end.

object Form1: TForm1  Left = 0  Top = 0  Caption = 'Form1'  ClientHeight = 407  ClientWidth = 645  Color = clBtnFace  Font.Charset = DEFAULT_CHARSET  Font.Color = clWindowText  Font.Height = -11  Font.Name = 'Tahoma'  Font.Style = []  OldCreateOrder = False  OnCreate = FormCreate  PixelsPerInch = 96  TextHeight = 13  object DBGrid1: TDBGrid    Left = 0    Top = 35    Width = 645    Height = 372    Align = alClient    DataSource = DataSource1    TabOrder = 0    TitleFont.Charset = DEFAULT_CHARSET    TitleFont.Color = clWindowText    TitleFont.Height = -11    TitleFont.Name = 'Tahoma'    TitleFont.Style = []  end  object Panel1: TPanel    Left = 0    Top = 0    Width = 645    Height = 35    Align = alTop    Caption = 'Panel1'    TabOrder = 1    object Button1: TButton      Left = 16      Top = 4      Width = 75      Height = 25      Caption = 'Button1'      TabOrder = 0      OnClick = Button1Click    end    object Button2: TButton      Left = 97      Top = 4      Width = 75      Height = 25      Caption = 'Button2'      TabOrder = 1      OnClick = Button2Click    end  end  object DataSource1: TDataSource    DataSet = ADODataSet1    Left = 184    Top = 112  end  object ADODataSet1: TADODataSet    CursorType = ctStatic    Parameters = <>    Left = 232    Top = 184  endend