o login está certo

DELIMITER $$
 CREATE TABLE `tbl_users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `username` varchar(15) NOT NULL,
  `firstlast_name` varchar(80) DEFAULT NULL,
  `password` varchar(45) DEFAULT NULL,
  PRIMARY KEY (`id`)
)$$
 DELIMITER ;

 DELIMITER $$
 DROP FUNCTION IF EXISTS `fun_valida_usuario`$$
 CREATE FUNCTION `fun_valida_usuario`(p_username VARCHAR(15)
                , p_password VARCHAR(45) ) RETURNS INT(1)
 BEGIN
 DECLARE _ret            INT(1) DEFAULT 0;
     SET _ret = IFNULL((SELECT DISTINCT 1
                       FROM tbl_users
                      WHERE `username` = p_username
                       AND `password` = MD5(p_password)),0);
 RETURN _ret;
 END$$
 DELIMITER ;

DELIMITER $$
CREATE PROCEDURE `proc_iae_tbl_users`(
p_opc varchar(1),
p_id int,
p_username varchar(15),
p_firstlast_name varchar(80),
p_password varchar(45))
BEGIN

IF ((p_opc = 'I') && (p_username != '') && (p_password != '')) THEN

  INSERT INTO tbl_users (id, username, firstlast_name, `password`) VALUES (p_id, p_username, p_firstlast_name, MD5(p_password));

ELSE

IF ((p_opc = 'E') && (p_id > 0)) THEN

   delete from tbl_users where id = p_id;

ELSE

IF ((p_opc = 'A')) THEN

  UPDATE tbl_users set id = p_id, username = p_username, firstlast_name = p_firstlast_name, `password` = p_password WHERE id = p_id;

ELSE
SELECT 'Você não pode realizar as alterações' AS Msg;
END IF;
END IF;
END IF;

END$$
DELIMITER ;

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, WideStrings, DBXMySql, DB, SqlExpr, FMTBcd, Provider, DBClient,
  StdCtrls, Mask, DBCtrls;

type
  TForm1 = class(TForm)
    SQLConnection1: TSQLConnection;
    ClientDataSet1: TClientDataSet;
    DataSetProvider1: TDataSetProvider;
    SQLQuery1: TSQLQuery;
    SQLQuery1id: TIntegerField;
    SQLQuery1username: TStringField;
    SQLQuery1firstlast_name: TStringField;
    SQLQuery1password: TStringField;
    DataSource1: TDataSource;
    ClientDataSet1id: TIntegerField;
    ClientDataSet1username: TStringField;
    ClientDataSet1firstlast_name: TStringField;
    ClientDataSet1password: TStringField;
    InsertUser: TButton;
    Edit1: TEdit;
    Edit2: TEdit;
    proc_iae_tbl_users: TSQLStoredProc;
    proc_iae_tbl_usersMsg: TStringField;
    Edit3: TEdit;
    Edit4: TEdit;
    Edit5: TEdit;
    VerifyLogin: TButton;
    Label1: TLabel;
    Label2: TLabel;
    SQLStoredProc1: TSQLStoredProc;
    SQLStoredProc1Value: TIntegerField;
    Label3: TLabel;
    DBEdit1: TDBEdit;
    DataSource2: TDataSource;
    SQLQuery2: TSQLQuery;
    SQLQuery2Valor: TIntegerField;
    Label4: TLabel;
    DBEdit2: TDBEdit;
    DataSource3: TDataSource;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.InsertUserClick(Sender: TObject);
begin
   proc_iae_tbl_users.Close;
   proc_iae_tbl_users.ParamByName('p_opc').Value:= 'I';
   proc_iae_tbl_users.ParamByName('p_username').Value:= Edit1.Text;
   proc_iae_tbl_users.ParamByName('p_firstlast_name').Value:= Edit2.Text;
   proc_iae_tbl_users.ParamByName('p_password').Value:= Edit3.Text;
   proc_iae_tbl_users.ExecProc;
end;

procedure TForm1.VerifyLoginClick(Sender: TObject);
begin
   // Aqui deve ficar o código para logar e verificar o login
end;

end.

DM.sql_login.Close;
  DM.sql_login.SQL.Clear;
  DM.sql_login.SQL.Add('SELECT fun_valida_usuario("'+edt_username.Text+'","'+edt_password.Text+'") AS Ret');
  DM.sql_login.Open;

  if (DM.sql_login['Ret'] = 1 ) then
    begin
       DM.sql_login.Close;
      Close;
    end
  else
    begin
      MessageBox(handle,'Usuário ou Senha estão incorretos','Aviso',mb_IconError + mb_OK);
    end;

StoredProc.Open;
try
    CredenciaisValidas := StoredProc.FieldByName('Result').AsInteger = 1;
finally
    StoredProc.Close;