Trying hard to add a common identifier with a bunch of rows in my query....Need guidance please

Question

Hi,
     Below is table structure as i/p of my query.
I/P
with temp1 as
(select 1 trans_id,'USD' currency,1500 amount,'B' orientation_buysell,'www' counterparty from dual
union
select 2,'USD',500,'S','www' from dual
union
select 3,'USD',1000,'S','www' from dual
union
select 4,'SGD',2500,'B','xyz' from dual
union
select 5,'SGD',500,'S','xyz' from dual
union
select 6,'SGD',1000,'S','xyz' from dual
union
select 7,'SGD',1000,'S','xyz' from dual
union
select 8,'JPY',3000,'B','yyy' from dual
union
select 9,'JPY',2000,'S','yyy' from dual
union
select 10,'JPY',500,'S','yyy' from dual
union
select 11,'JPY',500,'S','yyy' from dual
select * from temp1;
O/P should be like smthing below.
Alert_id start_trans_id end_trans_id currency orientation_buysell counterparty
1                  1                      2              USD                       B      www
1                  1                      3              USD                       B      www
2                  4                      5              SGD                       B      xyz
2                  4                      6              SGD                       B      xyz
2                  4                      7              SGD                       B      xyz
3                  8                      9              JPY                        B      yyy
3                  8                      10            JPY                        B      yyy
3                  8                      11            JPY                        B      yyy
So i have used below query, i got all my requirement done except Alert_id, could you please help me how to generate this alert id.
Query
Select a.trans_id Start_trans_id,b.trans_id End_trans_id,a.currency,a.orientation_buysell,a.counterparty 
from temp1 a
                 inner join
       temp1 b
                 on a.counterparty = b.counterparty
where a.orientation_buysell = 'B'
and      b.orientation_buysell='S'
order by a.trans_id,b.trans_id;
Actually these all data i need to pick from a table (here temp1), make its data as per my requirement(o/p) and also need to add a new column 'Alert_id' that should be populated as i have shown in o/p & Finally insert into a particular ALERT Table.
I am not getting this Alert id concept in my query, how to make this one generic.
Any help, would be really appreciable. Thanks

Answer 1

Hi,
So,
all the rows with the lowest value of trans_id need alert_id=1,
all the rows with the 2nd lowest value of trans_id need alert_id=2,
all the rows with the 3rd lowest value of trans_id need alert_id=3,
all the rows with the Nth lowest value of trans_id need alert_id=N.
That sounds like a job for the analytic DENSE_RANK function:
Select
       DENSE_RANK () OVER (ORDER BY  a.trans_id)  AS alert_id,    -- ***** NEW *****
       a.trans_id Start_trans_id,b.trans_id End_trans_id,a.currency,a.orientation_buysell,a.counterparty
from temp1 a
                 inner join
       temp1 b
                 on a.counterparty = b.counterparty
where a.orientation_buysell = 'B'
and      b.orientation_buysell='S'
order by a.trans_id,b.trans_id;
I added 1 line of code near the beginning; otherwise, this is exactly what you posted.