how to represent symmetric many to many relationship

Question

suppose i have a entity called USER and a relationship FRIENDSHIP exist between two USERs SO for that i have a table \'USER\' and a relationship table \'FRIENDSHIP\'

Answer 1

The obvious solution is to store just 1 record per each pair of friends. However, it makes harder to maintain uniqueness; all queries for getting/updating/removing friend relationship become more complex compared to "redundant" solution. Also, the solution with 2 records allows you maintain friends requests (E.g., UserA asks UserB to be a friend. UserB can confirm or reject this request). So I'd say redundancy is perfectly valid in this case.