Create random unique edges

[Cherie Pun]

Hi, I am trying to figure out a way to create random unique edges in the graph. I have written the following query to create a relationship between two users, but count always return 1 whether a new relationship is created or not. 

Is there a way to determine whether there was an existing edge or a new one was created? Thanks!

MATCH (a:USERS), (b:USERS)

WHERE id(a)=params[0] AND id(b)=params[1]

CREATE UNIQUE (a) -[r:TRUST] -> (b)

RETURN count(*)