Single row sub query error

Question

Hi All
I'm having the following query and its giving me "single row sub query returns more than one row". I did some research and all i could come across is using IN,ALL,ANY,NOT IN.... with the WHERE clause but not in the CASE statement so can any one please point me in the right direction?
SELECT ROW_NUMBER () OVER (PARTITION BY traffic_sample_id ORDER BY bin_data_id)
                                                              AS row_number_1,
       COUNT (bin_data_id) OVER (PARTITION BY traffic_sample_id) AS count_1,
       (CASE
           WHEN days != 2
              THEN (SELECT traffic_sample_id
                      FROM (SELECT ROW_NUMBER () OVER (PARTITION BY traffic_sample_id ORDER BY bin_data_id)
                                                                        AS rn,
                                   traffic_sample_id
                              FROM bin_data)
                     WHERE rn <= 48)
           ELSE (SELECT traffic_sample_id
                   FROM bin_data)
        END
       ) traffic_sample_id
  FROM (SELECT ROW_NUMBER () OVER (PARTITION BY t1.traffic_sample_id ORDER BY t1.bin_data_id)
                                                                AS ROW_NUMBER,
               COUNT (t1.bin_data_id) OVER (PARTITION BY t1.traffic_sample_id)
                                                                     AS COUNT,
               t1.traffic_sample_id, t1.bin_data_id, t1.end_intv_time,
               (  TO_DATE (t2.end_date, 'mmddyy')
                - TO_DATE (t2.start_date, 'mmddyy')
               ) AS days
          FROM bin_data t1, traffic_sample t2
         WHERE t1.traffic_sample_id = t2.traffic_sample_id(+))Thanks

Answer 1

Hi,
One of these two SELECT statements must be bringing back more thean one row:
              THEN (SELECT traffic_sample_id
                      FROM (SELECT ROW_NUMBER () OVER (PARTITION BY traffic_sample_id ORDER BY bin_data_id)
                                                                        AS rn,
                                   traffic_sample_id
                              FROM bin_data)
                     WHERE rn <= 48)
           ELSE (SELECT traffic_sample_id
                   FROM bin_data)