Question

i have the following exception:

here is the relevant code parts:
Server.Proxy.update_allLogOut: (line 65 is the while bracket)

    public void update_allLogOut ()
{
    try 
    {
        ResultSet rs;
        stmt = conn.createStatement();
        rs = stmt.executeQuery("SELECT * FROM sysuser WHERE login=1");
        while(rs.next())
        {
            stmt.executeUpdate("UPDATE sysuser SET login=0");
        }
        rs.close();
    } catch (SQLException e) {e.printStackTrace();}

}   

Server.Server.:

      public Server(int port) 
 {
    super(port);
    func.update_allLogOut();
  }

main:

Server sv = new Server(5555);

i must point out that 99% of times it runs with no exceptions.. but several times i get this exception that i cant figure out why it happens. any ideas? it is clear that something is done wrong yet all similar topics here have not given the answer in this case…

Answer 1

You are using stmt to both iterate over the results of SELECT and to UPDATE inside the loop. This doesn’t work since the moment you execute the UPDATE, the result set associated with the SELECT gets closed.

To fix, use two separate Statement objects.