String DBdriver = "com.ora.jdbc.Driver";
String DataURL = "jdbc:db://localhost:5112/users";
String loginName = "stackoverflow";
String passwd = "codeReview";
Class.forName(DBdriver);
Connection conn = DriverManager.getConnection(DataURL, loginName, passwd);
String Username = request.getParameter("USER");
String Password = request.getParameter("PASSWORD");
int iUserID = -1;
String loginUser = "";
String sel = "SELECT UserID, Username FROM USERS WHERE Username = '"
    +Username + "' AND Password = '" + Password + "'";
Statement selectStatement = conn.createStatement ();
ResultSet result = selectStatement.executeQuery(sel);
if (result.next()) {
       iUserID = result.getInt(1);
       loginUser = result.getString(2);
}
PrintWriter wr = response.getWriter ();
if (iUserID >= 0) {
       wr.println ("you logged in: " + loginUser);
} else {
       wr.println ("you cannot login in !Access Denied!")
}

String DataURL = "jdbc:db://localhost:5112/users";
String loginName = "stackoverflow"

final boolean hasUser = result.next();
if (hasUser) {
    iUserID = result.getInt(1);
    loginUser = result.getString(2);
} else {
    wr.println ("you cannot login in !Access Denied!");
}

final boolean hasUser = result.next();
if (!hasUser) {
    wr.println ("you cannot login in !Access Denied!");
    return; // etc.
}
final int userID = result.getInt(1);
final String loginUser = result.getString(2);

userID = result.getInt("UserID");
loginUser = result.getString("Username);

PrintWriter wr = response.getWriter ();

PrintWriter wr = response.getWriter();

PrintWriter writer = response.getWriter();