Help with creating a sub-query

Question

Hi,
I have a table, comprised of three columns: patient_id, observation, and pain_score
Pat_id, obs_num, pain_score
12345, 1, 4
12345, 2, 6
12345, 3, 8
98765, 1, 2
98765, 2, 4
98765, 3, 6
I need to see the percent change from observation 1 to observation 3 per patient. So basically I need to isolate the 4 and the 8 pain_score for patient 12345; and the 2 and 6 pain_score for patient 98765. All patients have 3 observation periods.
Thanks for the help.
Rich

Answer 1

test@XE> set echo on
test@XE>
test@XE> @test3
test@XE> --
test@XE> with t as (
  2    select 12345 as pat_id, 1 as obs_num, 4 as pain_score from dual union all
  3    select 12345, 2, 6 from dual union all
  4    select 12345, 3, 8 from dual union all
  5    select 98765, 1, 2 from dual union all
  6    select 98765, 2, 4 from dual union all
  7    select 98765, 3, 6 from dual)
  8  --
  9  select pat_id,
10         obs_num,
11         pain_score,
12         lead(pain_score) over (partition by pat_id order by obs_num) as next_pain_score,
13         case obs_num
14           when 1 then (lead(pain_score) over (partition by pat_id order by obs_num) - pain_score)/pain_score*100||' %'
15           else null
16         end as pct_change
17  from t
18  where obs_num in (1, 3);
    PAT_ID    OBS_NUM PAIN_SCORE NEXT_PAIN_SCORE PCT_CHANGE
     12345          1          4               8 100 %
     12345          3          8
     98765          1          2               6 200 %
     98765          3          6
test@XE>
test@XE>
test@XE>isotope