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Question

为什么我在进行密码登陆的时候，输入正确密码会显示表中没有这个字段

Answer 1

这是我的代码
unit login;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, jpeg, ExtCtrls, StdCtrls, Buttons, DsFancyButton,Registry;type
  Tlogin1 = class(TForm)
    Image1: TImage;
    Edit2: TEdit;
    DsFancyButton1: TDsFancyButton;
    DsFancyButton2: TDsFancyButton;
    Image3: TImage;
    edit1: TComboBox;
    procedure DsFancyButton2Click(Sender: TObject);
    procedure DsFancyButton1Click(Sender: TObject);
    procedure FormActivate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  login1: Tlogin1;implementation
uses index, DM;{$R *.dfm}procedure Tlogin1.DsFancyButton2Click(Sender: TObject);
begin
login1.close;
end;procedure Tlogin1.DsFancyButton1Click(Sender: TObject);
var
  Reg:TRegistry;
begin
  with DM1 do
  begin
    ADOQuery1.Close;
    ADOQuery1.SQL.Clear;
    ADOQUery1.SQL.Add('select * from users where username='''+Edit1.Text+'''');
    ADOQuery1.Open;
     if edit1.Text=''   then
     begin
     showmessage('请输入用户名');
     Edit2.Text:='';
     Edit1.SetFocus;
     Exit;
     end
     else
    if Edit2.Text<>ADOQuery1.FieldByName('Password').AsString then
    begin
      showmessage('密码不正确，请重新输入');
      Edit2.Text:='';
      Edit2.SetFocus;
      Exit;
    end
    else
    begin
      Reg:=TRegistry.Create;
      Reg.RootKey:=HKEY_CURRENT_USER;
      if Reg.OpenKey('\Software\shijuan',true) then
      begin
        Reg.WriteString('NowUser',Edit1.Text);
      end;
      Reg.CloseKey;
      Reg.Free;
       main.showmodal;
     end;
     close;
    end;
  end;procedure Tlogin1.FormActivate(Sender: TObject);
begin
  with DM1 do
  begin
    ADOQuery1.Close;
    ADOQuery1.SQL.Clear;
    ADOQuery1.SQL.Add('select userName from Users');
    ADOQuery1.Open;
    ADOQuery1.First;    Edit1.Items.Clear;
    while not ADOQuery1.Eof do
    begin
      Edit1.Items.Add(ADOQuery1.FieldValues['UserName']);
      ADOQuery1.Next;
    end;
  end;
end;end.

Answer 2

ADOQUery1.SQL.Add('select * from users where username='''+Edit1.Text+'''');
这句话好像有问题吧，看看引号的写法，好像 有问题，你可以把
showmessage（adoquery1.sql.text).然后看看sql语句是否正确。