sum of columns and list difference between rows - sql

Question

I am trying to get the difference between rows based on group by SELL_ID on the below table,
table1 - (table formatting courtesy of GitHub)
+---------+---------+----------+----------+------------------+---------+
| seq_ID | REQ_ID | CALL_ID | SELL_ID | REGION | COUNT |
+---------+---------+----------+----------+------------------+---------+
| 1 | 123 | C001 | S1 | AGL | 510563 |
| 2 | 123 | C001 | S1 | USL | 122967 |
| 3 | 123 | C001 | S1 | VALIC | 614106 |
| 4 | 123 | C001 | S2 | Inforce | 1247636 |
| 5 | 123 | C001 | S2 | NB | 0 |
| 6 | 123 | C001 | S3 | Seriatim Summary | 1247636 |
+---------+---------+----------+----------+------------------+---------+
I am trying to get the results as below,
table2 -
+---------+---------+----------+----------+-------+
| seq_ID | REQ_ID | CALL_ID | Summary | COUNT |
+---------+---------+----------+----------+-------+
| 1 | 123 | C001 | S1_vs_S2 | 0 |
| 2 | 123 | C001 | S2_vs_S3 | 0 |
| 3 | 123 | C001 | S3_vs_s1 | 0 |
+---------+---------+----------+----------+-------+
S1_vs_S2 is the difference between (sum(count) from table1 where sell_id='S1') and (sum(count) from table1 where sell_id='S2')
Below is the code that i am using, But couldn't fetch the results,
INSERT INTO table2 (SEQ_ID, REQ_ID,call_id,summary,count)
SELECT min(seq_id) seq_id
, req_id
, call_id
, S1_vs_S2
,((SELECT sum(c2) FROM TABLE_STG_CTRL WHERE source='S1')-
SELECT sum(c2) FROM TABLE_STG_CTRL WHERE source='S2'))
FROM table1
GROUP BY req_ID, Ctrl_ID, c1, source
ORDER BY SEQ_ID ;

Answer 1

Does this do what you want?
select req_id, call_id, sell_id,
lead(sell_id) over (partition by req_id, call_id order by seq_id) as next_sell_id,
(cnt -
lead(cnt) over (partition by req_id, call_id order by seq_id)
) as diff
from (select req_id, call_id, sell_id, sum(count) as cnt, min(seq_id) as seq_id
from t
group by req_id, call_id, sell_id
) t

Answer 2

At first group data on sell_id, req_id, call_id. This is subquery t in my code. Then self join properly this result and show difference. The only problem is to construct join condition carefully:
demo with your sample data
with t as (
select sell_id sid, req_id, call_id, sum(cnt) cnt
from table1
group by sell_id, req_id, call_id )
select case t1.sid when 'S1' then 1 when 'S2' then 2 when 'S3' then 3 end id,
t1.req_id, t1.call_id, t1.sid||'_vs_'||t2.sid call_id, t1.cnt - t2.cnt diff
from t t1
join t t2 on t1.req_id = t2.req_id
and t1.call_id = t2.call_id
and (t1.sid, t2.sid) in (('S1', 'S2'), ('S2', 'S3'), ('S3', 'S1'))
order by id
BTW count is Oracle reserved word, please avoid such names when naming columns etc.