unit1.pas

一系列DELPHI的控件如何使用的例子,例子有的比较简单,但是能详细的说明了控件的使用,对许多刚涉足DELPHI的朋友会很有帮助的

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, DBTables, Grids, DBGrids, ExtCtrls, StdCtrls;

type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    ComboBox1: TComboBox;
    Button1: TButton;
    Panel1: TPanel;
    DBGrid1: TDBGrid;
    Query1: TQuery;
    DataSource1: TDataSource;
    Query2: TQuery;
    procedure FormCreate(Sender: TObject);
    procedure ComboBox1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
   with combobox1 do
    begin
      items.Clear;
      items.Add('全部');
      query2.First;
      while not query2.Eof do
        begin
        items.Add(query2.fieldbyname('name').AsString);
        query2.Next;
        end;
    end;
    combobox1.ItemIndex:=0;
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
   with query1 do
    begin
    sql.Clear;
    if combobox1.Text ='全部' then
     sql.Add('select * from country')
    else
     begin
      sql.Add('select * from country where name=:demo');
      parambyname('demo').AsString:=combobox1.Text;
     end;
     open;
    end;

end;

end.