有关if 语句的问题
unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, Grids, DBGrids, StdCtrls, Buttons, DB, DBTables, ADODB, Mask,
DBCtrls;

type
TForm1 = class(TForm)
con1: TADOConnection;
ds1: TDataSource;
btn1: TBitBtn;
dbgrd1: TDBGrid;
qry1: TADOQuery;
dbedtID: TDBEdit;
btn2: TButton;
btn3: TButton;
procedure btn1Click(Sender: TObject);
procedure btn2Click(Sender: TObject);
procedure btn3Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btn1Click(Sender: TObject);
begin
qry1.Close ;
qry1.SQL.Clear ;
qry1.SQL.Text:='select * from 信息表';
qry1.Open ;
end;
procedure TForm1.btn2Click(Sender: TObject);
begin
if dbedtID.Text <> null then
ShowMessage('保存成功!')
else
ShowMessage('报存失败！');
end;

procedure TForm1.btn3Click(Sender: TObject);
begin
Application.Terminate ;
end;

end.
运行后无论dbedtID.Text是否为空都提示‘保存成功’else 后好像没起作用，该如何修改，刚开始学delphi
[解决办法]
if dbedtID.Text <> null then
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
if trim(dbedtID.Text)<>'' then
[解决办法]
1楼是对的。
[解决办法]

if dbedtID.Field.IsNull then
或
if dbedtID.Text<>'' then
[解决办法]
楼上没错！~！！
[解决办法]
delphi里面的Null应该是nil吧？
[解决办法]
楼上全部+1
[解决办法]
if length(trim(dbedtID.Text))=0 then
[解决办法]