How to get distinct values in a comma separated list of email addresses?

Question

Hi Friends,
I have a cursor which fetches email address along with some other columns. More than one record can have same email address.
Ex
CURSOR C1 IS
SELECT 1 Buyer,'XX123' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX223' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 1 Buyer,'XX124' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX224' PO, '[email protected]' Buyer_email from dualNow, i open the cursor write the contents into a file and also form a comma separated list of buyer emails as follows
for cur_rec in c1
LOOP
--write contents into a file
l_buyer_email_list := l_buyer_email_list||cur_rec.buyer_email||',';
END LOOP
l_buyer_email_list := RTRIM(l_buyer_email_list,',');
The buyer email list will be like: '[email protected],[email protected],[email protected],[email protected]'
Inorder to avoid duplicate email address in the list, i can store each of this value is a table type variable and compare in each iteration whether the email already exist in the list or not.
Is there any other simpler way to achieve this?
Regards,
Sreekanth Munagala.

Answer 1

If you are using oracle version 11, you can use listagg function
with c as
(SELECT 1 Buyer,'XX123' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX223' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 1 Buyer,'XX124' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX224' PO, '[email protected]' Buyer_email from dual
select buyer, listagg(buyer_email,',') within group (order by  buyer) 
from c
group by buyer
order by buyerFor prior versions
{cod}
with c as
(SELECT 1 Buyer,'XX123' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX223' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 1 Buyer,'XX124' PO, '[email protected]' Buyer_email from dual
UNION ALL
SELECT 2 Buyer,'XX224' PO, '[email protected]' Buyer_email from dual
select buyer, rtrim(xmlagg(xmlelement(e,buyer_email||',').extract('//text()')),',')
from c
group by buyer
order by buyer