Retrieving a specific value from mysql database based on parameters
public void getUser(String username, String password)throws SQLException{
 String qry = "SELECT UserName From USER....";

   Connection con = null;
   PreparedStatement stmt = null;

   try{

con = DriverManager.getConnection("URL");
stmt = con.prepareStatement(qry);
stmt.executeUpdate();

Connection con = null;
PreparedStatement stmt = null;
ResultSet rs = null;
String qry = "SELECT UserName From USER where username=? and password=?";
   try{

         con = DriverManager.getConnection("URL");
         stmt = con.prepareStatement(qry);
         stmt.setString(1, username);
         stmt.setString(2, password);
         rs =  stmt.executeQuery();
         while (rs.next()) {
               System.out.println(rs.getString("UserName"));
         }
        ...

Connection c = null;
PreparedStatement s = null;
try {
  c = DriverManager.getConnection("URL");
  s = c.prepareStatement("SELECT fullname FROM user WHERE username=? and password=?");
  s.setString(1, username);
  s.setString(2, password);

  ResultSet rs = s.executeQuery();
  if(rs.next())
    return rs.getString("fullname");

  return null; // no user found!
} catch(SQLException e) {
  System.err.println(e.getMessage());
} finally {
   // close s and c
}