demo2.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 demo2;

interface

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

type
  TForm1 = class(TForm)
    Query1: TQuery;
    DataSource1: TDataSource;
    DBGrid1: TDBGrid;
    Panel1: TPanel;
    RadioGroup1: TRadioGroup;
    DateTimePicker1: TDateTimePicker;
    DateTimePicker2: TDateTimePicker;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    ComboBox1: TComboBox;
    Label4: TLabel;
    ComboBox2: TComboBox;
    Panel2: TPanel;
    procedure DateTimePicker1Change(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
     procedure RefreshQuery;
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
procedure TForm1.RefreshQuery;
begin
   with query1 do
    begin
    close;
    SQL.clear;
    SQL.add('SELECT * FROM employee ');
    case RadioGroup1.ItemIndex of
         0: begin
            SQL.add('where hiredate>=:Qdate1 and hiredate<=:Qdate2');
            parambyname('Qdate1').AsDate :=DateTimePicker1.datetime;
            parambyname('Qdate2').AsDate :=DateTimePicker2.datetime;
            end;
         1: begin
            SQL.add('where salary>=:Qsalary1 and salary<=:Qsalary2');
            parambyname('Qsalary1').AsFloat:=strtofloat(combobox1.Text);
            parambyname('Qsalary2').AsFloat:=strtofloat(combobox2.Text);
            end;
            end;
    open;
    Panel2.Caption:='满足条件的记录有'+inttostr(query1.RecordCount)+'条';
    end;
end;



procedure TForm1.DateTimePicker1Change(Sender: TObject);
begin
   RefreshQuery;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
    combobox1.ItemIndex:=0;
    combobox2.ItemIndex:=0;
    RadioGroup1.ItemIndex:=0;
end;

end.