public void connect(String url, String user, String pass) throws ConnectionException {
		if(url  == null || url.equals("") ) throw new IllegalArgumentException("Illegal url: "  + url);
		if(user == null || user.equals("")) throw new IllegalArgumentException("Illegal user: " + user);
		if(pass == null || pass.equals("")) throw new IllegalArgumentException("Illegal pass: " + pass);
		
		try {
			// Register JDBC driver
			Class.forName(DBImpl.JDBC_DRIVER);
			// Open a connection
			this.conn = DriverManager.getConnection(url, user, pass);

		} 
		catch (ClassNotFoundException | SQLException e) 
		{ e.printStackTrace();throw new ConnectionException(); }
		
	}