Most efficient way to link records together like in FaceBook?

Hi Everyone,

On sites like FaceBook you can add friends where many people are linked to others. How is the best way to do this? Is there a single table that has all of the links with two fields - if you have 5 friends, your ID is in one field of 5 records and each of their IDs are in the other fields? For a popular site that table will have millions of records!

The only other way is to add all of your friend's IDs to one field with a seperator and split them up to list. I suppose you could have multiple fields holding these IDs with several in each one.

Or is there another way I'm not thinking about? I work with MSSQL mostly but we also have a client with the latest AS400 and that AS400 blows away anything I have ever seen as far as speed!!

Warren

The standard for a many-to-many relationship is as you descriped; your id in 5 rows with 1 row for each of the 5 friends.