ResultSet rs;
PreparedStatement st = MyConnection.prepareStatement("Select * from logindetails where Username = ? and Password = ?");
st.setString(1, username);
st.setString(2, password);
while (rs.next() )
{
//login correct = true, redirect
}
rs.close();
MyConnection.close();
The problem with this is I cannot use the next() in the while loop using the PreparedStatement, because I want to search the database with the parameters input by the user.
How can I fix this?
You don't need while (rs.next()) because your PreparedStatement has already queried the result set using the username and password you set. Instead, use if statement to test the result set:-
// returns AuthenticatedUser object if authentication is successful, otherwise null
public AuthenticatedUser authenticate(String username, String password) {
PreparedStatement st = ...;
st.setString(1, username);
st.setString(2, password);
ResultSet rs = st.executeQuery();
AuthenticatedUser user = null;
//login valid because there is something from the result set, then create user object
if (rs.next() ) {
// set all the useful user information in this POJO
user = new AuthenticatedUser(username, rs.getString("name"), rs.getString("whatever_important_info"));
}
... // close resultset, preparedStatement, connection, clean up, etc.
return user;
}
From your servet/controller, you can do something like this to handle the page redirection:-
// call the method above to get the user object based on the provided username and password
AuthenticatedUser user = dao.authenticate(username, password);
// successful authentication
if (user != null) {
// set user object in session so that you don't need to query the database for user info again and again
session.setAttribute("user", user);
// redirect to welcome page
request.getRequestDispatcher("/your-welcome-page").forward(request, response);
}
else {
// redirect to login page if authentication fails
request.getRequestDispatcher("/login-page").forward(request, response);
}
Not sure I'm understanding your question correctly but I'm guessing you want to iterate through the result set and access the column data...
rs = st.executeQuery();
while (rs.next() ) {
rs.getString("columnname");
}
If this is for a production application (as opposed to learning or homework), why are you not using an abstraction layer like iBatis to insulate you from this biolerplate?
whileloop, you're missing the liners = st.executeQuery();, but I'm guessing that's not the problem. Can you clarify your question? It's not at all clear what you're asking. If you add the line I just mentioned, the code should work fine, and sure return any matching rows.