Efficient way to store unordered pair in a mysql table

Question

I am working with twitter data and need to store uid and friendId pair in a mysql table. My purpose is to create a network of friends and followers with the help of the table later.

I want to avoid duplicate pairs like (uid, friendId) and (friendId, uid) in the table.

Thank you

Answer 1

to avoid duplicate pairs do check uid < friendId before inserting.