How to traverse a tree in SQL? Sybase edition
It's bugging me that this question doesn't have at least one answer.  So...

You could use a mix of primary/foreign keys within the table per Joe Celko.  Alternatively, you might want to consider a closure table.

Generally, the table referencing itself seems to be the most common method for handling this.  Of course, you would have to consider looping.  Some DBMSs have CTEs which can use Recursion, so the looping is inherent in the CTE.  For Sybase, you'll probably have to throw a loop in code somewhere.