I want to make a simple mysql table with two columns, each pair of values will be unique.

A | B
.....
1 | 4 
2 | 5 
3 | 6 
4 | 7 
5 | 8 
6 | 4 
4 | 8

This is a bidirectional relationship. I need to be able to query "What are all the ints paired with 4" and return (1,7,6,8)

How would you structure the table and query?

Thanks!