急！！！谁帮我看看，delphi 登陆界面代哪里有错。

Question

procedure TForm1.Edit2MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
      if edit1.Text='' then
      begin
      application.MessageBox('用户名不能为空！','警告',mb_ok);
      edit1.SetFocus;
      end;end;procedure TForm1.Button1Click(Sender: TObject);
var
   f1:Tform2;
   f2:Tform3;
begin
    if edit2.Text='' then
        begin
           application.MessageBox('密码不能为空！','警告',mb_ok);
           edit2.SetFocus;
        end
    else
        begin           adoquery1.Close;
           adoquery1.SQL.Clear;
           adoquery1.SQL.Add('select * from users where ID=:nu and  password=:pa');
           adoquery1.Parameters[0].Value:=Edit1.Text;
           adoquery1.Parameters[1].Value:=Edit2.Text;
           adoquery1.open;
        end;
        if adoquery1.RecordCount>0 then
        begin
          if  Trim(adoquery1.FieldByName('admin').AsString)='true' then
              begin
               form1.Hide;
               f1:=Tform2.Create(application);
               try
                 f1.showmodal;
               finally
                 f1.free;
                end;
               end          else if Trim(adoquery1.FieldByName('admin').AsString)='false' then
               begin
               form1.Hide;
               f2:=Tform3.Create(application);
               f2.show;
               end;
        end
        else
             begin
             showmessage('对不起，该用户不存在!');
             form1.Edit1.Text:='';
             form1.Edit2.Text:='';
             end;
end;
刚刚学delphi，很多还不会，关键是查询用户名和密码那一点。哪位高手指点一下，在线等~~~~~

Answer 1

填写ID和密码后就进不了了，怀疑是SQL的问题。怎么找也找不到。求助~~

Answer 2

procedure TForm1.Button1Click(Sender: TObject); 
var 
  f1:Tform2; 
  f2:Tform3; 
begin 
    if edit2.Text='' then 
        begin 
          application.MessageBox('密码不能为空！','警告',mb_ok); 
          edit2.SetFocus; 
          exit;
        end;
    //else 
        begin           adoquery1.Close; 
          adoquery1.SQL.Clear; 
          adoquery1.SQL.Add('select * from users where ID=:nu and  password=:pa'); 
          adoquery1.Parameters[0].Value:=QuotedStr(Edit1.Text); 
          adoquery1.Parameters[1].Value:=QuotedStr(Edit2.Text); 
          adoquery1.open; 
        end; 
        if adoquery1.RecordCount>0 then 
        begin 
          if  Trim(adoquery1.FieldByName('admin').AsString)='true' then 
              begin 
              form1.Hide; 
              f1:=Tform2.Create(application); 
              try 
                f1.showmodal; 
              finally 
                f1.free; 
                end; 
              end 
          else if Trim(adoquery1.FieldByName('admin').AsString)='false' then 
              begin 
              form1.Hide; 
              f2:=Tform3.Create(application); 
              f2.show; 
              end; 
        end 
        else 
            begin 
            showmessage('对不起，该用户不存在!'); 
            form1.Edit1.Text:=''; 
            form1.Edit2.Text:=''; 
            end; 
end; 

Answer 3

          adoquery1.Close; 
          adoquery1.SQL.Clear; 
          adoquery1.SQL.Add('select * from users where ID=:nu and  password=:pa'); 
          adoquery1.Parameters[nu].Value:=Edit1.Text; 
          adoquery1.Parameters[pa].Value:=Edit2.Text; 
          adoquery1.open; 

Answer 4

adoquery1.Close; 
adoquery1.SQL.Clear; 
adoquery1.SQL.Add('select * from users where ID=:nu and  password=:pa'); 
adoquery1.Parameters[0].Value:=QuotedStr(Edit1.Text); 
adoquery1.Parameters[1].Value:=QuotedStr(Edit2.Text); 
adoquery1.open;可以改成adoquery1.Close; 
adoquery1.SQL.Clear; 
adoquery1.SQL.Add('select * from users where ID='+edit1.text+' and password='''+edit2,text+''''); 
adoquery1.open;

Answer 5

     if  Trim(adoquery1.FieldByName('admin').AsString)='true' then 
              begin
这一句是什么意思啊，好像意义不大只要  if adoquery1.RecordCount>0 then 这个条件为真就显示窗口就好了吧？