学习 SQL 语句 - Select(1): 指定表

本文来自：万一

//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}

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本例效果图:

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代码文件:

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unit Unit1;

interface

uses
  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.