登陆问题，大家帮帮我吧

Question

我主要想实现的是个简单的登陆问题
以前都用combobox做
现在不想用哪个了
但是每次都是输入第一条数据是对的
第二条数据数据就找不到
所以我放了个循环，结果出现了死循环
源程序如下：
unit Unit2;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, DB, ADODB;type
  TForm2 = class(TForm)
    Edit1: TEdit;
    Edit2: TEdit;
    ADOTable1: TADOTable;
    DataSource1: TDataSource;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form2: TForm2;implementationuses Unit1;{$R *.dfm}procedure TForm2.Button1Click(Sender: TObject);
var
conn:string;
mypath:string;
mimi:string;
begin
conn:='Provider=Microsoft.Jet.OLEDB.4.0;Data Source='+mypath+'data\student.mdb;Persist Security Info=False';
adotable1.ConnectionString:=conn;
adotable1.TableName:='admin';
adotable1.Open;
adotable1.First;
while not adotable1.Eof do
begin
if (trim(edit1.Text)=trim(adotable1.Fields[1].AsString)) and  (trim(edit2.Text)=trim(adotable1.Fields[2].AsString)) then
      begin
           form1.Show;
           adotable1.Next;
      end;
end;
   if edit1.Text='' then
   begin
      showmessage('用户名不能不填吧？！！');
      edit1.SetFocus;
   end
   else if edit2.Text='' then
          begin
            showmessage('密码忘了写！！');
            edit2.SetFocus;
          end
      else
 end;procedure TForm2.FormCreate(Sender: TObject);
begin
   edit1.Text:='';
   edit2.Text:='';
end;end.

Answer 1

adotable1.First;
while not adotable1.Eof do
begin
if (trim(edit1.Text)=trim(adotable1.Fields[1].AsString)) and  (trim(edit2.Text)=trim(adotable1.Fields[2].AsString)) then
      begin
           form1.Show;
           adotable1.Next;
      end;
adotable1.next;
end;

Answer 2

while not adotable1.Eof do
begin
if (trim(edit1.Text)=trim(adotable1.Fields[1].AsString)) and  (trim(edit2.Text)=trim(adotable1.Fields[2].AsString)) then
      begin
           form1.Show;
           adotable1.Next;///////去掉
      end;
 adotable1.Next;///////在这里加上
end;

Answer 3

不好意思，上面的也是错的，应该是这样：
while not adotable1.Eof do
begin
if (trim(edit1.Text)=trim(adotable1.Fields[1].AsString)) and  (trim(edit2.Text)=trim(adotable1.Fields[2].AsString)) then
      begin
           form1.Show;
           adotable1.Next;///////去掉
            break;
      end;
 adotable1.Next;///////在这里加上
end;

Answer 4

1、先看这一段，作用是如果用户名和密码都正确就FORM1出现，对吧？
那么
while not adotable1.Eof do
begin
  if (trim(edit1.Text)=trim(adotable1.Fields[1].AsString)) //这个TRIM我觉得不用加
  and (trim(edit2.Text)=trim(adotable1.Fields[2].AsString)) then  //这里是输入都
                                                                    正确了
   begin
      form1.Show;
      adotable1.Next;//干吗还要下一条记录？
   end;
end;
2、再看这一段
if edit1.Text='' then
   begin
      showmessage('用户名不能不填吧？！！');
      edit1.SetFocus;
   end
   else if edit2.Text='' then
          begin
            showmessage('密码忘了写！！');
            edit2.SetFocus;
          end
      else
 end;
按照逻辑上讲应该是先判断有没有空的，再判断是否正确吧？所以我觉得这么写好一点
procedure TForm2.Button1Click(Sender: TObject);
var
conn:string;
mypath:string;
mimi:string;
begin
   if edit1.Text='' then
   begin
      showmessage('用户名不能不填吧？！！');
      edit1.SetFocus;
      exit;
   end 
   else 
   if edit2.Text='' then
   begin
      showmessage('密码忘了写！！');
      edit2.SetFocus;
      exit;
   end
   else
   begin
      conn:='Provider=Microsoft.Jet.OLEDB.4.0;Data     
      Source='+mypath+'data\student.mdb;Persist Security Info=False';
      adotable1.ConnectionString:=conn;
      adotable1.TableName:='admin';
      adotable1.Open;
      adotable1.First;
      while not adotable1.Eof do
      begin
         if (trim(edit1.Text)=adotable1.Fields[1].AsString)
         and (trim(edit2.Text)=adotable1.Fields[2].AsString) then
         begin
            form1.Show;
         end 
         else
         adotable1.Next;
      end
      else
      showmessage('登陆失败');
   end;
end;
我没有调试，可能有些小问题自己调调吧。

Answer 5

错了     adotable1.Next;
      end
      else
      showmessage('登陆失败');
   end;
这一段改成
     adotable1.Next;
     end;
   end
   else
   showmessage('登陆失败');

Answer 6

还是有问题啊
showmessage('用户名不能不填吧？！！');
showmessage('密码忘了写！！');
因该放哪啊？
虽然可以循环了
但不管你的密码，用户名对不对
他都要showmessage