how to retain attributes ina class

[narjis]

I am making a project by designing my own MVC model. In this the user accesses controller class which further calls model class which accesses the database by $dbh attiribute defined public. My View is a script which calls different pages. In the constructor of model I'm establishing connection with the database. Firstly I construct the model object when the user accesses i.e. in the controller class to check in the databse then if the username is not present in the dtaabse I want to insert his info in the database for that I again calla model class but this time I again have to establish connection. Is the $dbh firstly constructed is lost like dangling pointers in C++. Do I have to  worry about it. If yes how can I solve this problem.