Question

当我使用正确的用户名和密码登录我的应用程序时，我收到错误的用户名或密码的错误消息，然后下次我点击登录按钮登录工作正常。我是一个delphi业余爱好者所以不要难以评判我。

type
  TfmLogin = class(TForm)
    pnlMain: TPanel;
    lblUserName: TLabel;
    SQLConnection: TSQLConnection;
    DataSource: TDataSource;
    ClientDataSet: TClientDataSet;
    SQLQuery: TSQLQuery;
    DataSetProvider: TDataSetProvider;
    edtUserName: TEdit;
    lblPassword: TLabel;
    edtPassword: TEdit;
    btnRegistration: TButton;
    btnLogin: TButton;
    SQLTable: TSQLTable;
    procedure btnRegistrationClick(Sender: TObject);
    procedure btnLoginClick(Sender: TObject);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  fmLogin: TfmLogin;

implementation

这是匹配功能

function MatchPass(Table : TSQLTable; const UserName, Password : string): Boolean; 
begin
 Result := Table.Locate('Username;Password', VarArrayOf([username,password]),[]);
end;

这是登录按钮程序

procedure TfmLogin.btnLoginClick(Sender: TObject);
var
UserName : string;
Password : string;
begin
 UserName := edtUserName.Text;
 Password := edtPassword.Text;

     if(MatchPass(SQLTable, UserName, Password)) then    //1.Why first time returns false
     begin
      with TfmMain.Create(nil) do
        try
          ShowModal; //3.And opens my main form
        finally
          free;
        end;
     end
      else
    ShowMessage('Wrong name or pass'); //2.And enters else and the second time returns true
    end;

Answer 1

为什么不（从头）：

procedure TLogin_Form.Button1Click(Sender: TObject);
begin
Query1.Active:=false;
Query1.SQL.Clear;
Query1.SQL.Text:= 'select [user],[password] from  users where  [user] ='+QuotedStr(cxlookupcombobox1.text) +' and [password]='+QuotedStr(cxTextEdit1.Text);
Query1.Open;
if Query1.FieldByName('password').AsString<>''
then  begin
ModalResult := mrOK ;
end else
ModalResult := mrNone;

你不需要匹配任何东西，因为密码必须匹配。

Delphi XE登录错误

1 个答案: