Best way to set up a member database

[Milo Vicente]

Dear All,

I´m setting up a database with what may turn out to be a large number of members. So I have a a table in the db called users, containing usernames, passwords etc. I´ve made another table with messages, where the messages between users are stored.
Now my problem is what I do with users and their friends lists. I could make a table more for that purpose only, where each row again is a username, and then each column contains a friend of the user. Or I could have just one row in the first table, where friends are separated by for instance a "/", and will be parsed by a PHP script. More complicated for me, but maybe alot more effecient.
Or, is there a different approach you could recommend?

Thanks in advance!