Friend Suggestions (Friends of Friends)

Suggest friends of friends: for each user return every user they are not yet friends with who shares at least one mutual friend, with the number of mutual friends. Friendships are stored once per pair and are mutual. Order by user, suggestion.

Table schema

Friends(user1 INT, user2 INT)

Sample data

user1 | user2
1 | 2
2 | 3
3 | 4