Associating Rank to Event using Date

CREATE TABLE FIRST_REV_DATE_TABLE AS 
     SELECT
     anonymous_id, rev_date as first_rev_date
 FROM
     ( 
     SELECT anonymous_id,     
         DATE_TRUNC('d', sent_at) as rev_date,
         RANK() OVER (PARTITION by anonymous_id ORDER BY sent_at DESC) as rank,
     FROM
                RUDDER.track
     WHERE
               event=’revenue’         
     )
 WHERE
    rank = 1