Session Guidance

[eluser]TerryT[/eluser]
New to CI and have a couple of questions on sessions. I have read the User Guide and searched the forums prior to posting, but haven't been able to figure it out.

I am storing sessions in a database. That is working fine. What code do I need to put in my Controllers to validate the session cookie against the database?

2. How do I read the userdata column in the session table? Here's some output:

a:6:{s:5:"email";s:15:"admin@admin.com";s:2:"id";s:1:"1";s:7:"user_id";s:1:"1";s:8:"group_id";s:1:"1";s:5:"group";s:5:"admin";s:17:"flash:new:message";s:29:"<p>Logged In Successfully</p>";}

What does the a:6: mean? 6 attributes?

Terry