LISTAGG Query "ORA-00937: not a single-group group function" [duplicate]

Question

I'm trying to create a join with a list of comma separated values. For example:

rule_id | attribute_id
----------------------
1       | a
1       | b
2       | c
2       | d

should be:

rule_id | attribute_id
----------------------
1       | a,b
2       | c,d

I am attempting to do so using LISTAGG. However, with the below code, I'm getting ORA-00937: not a single-group group function. I noticed a FOR PATH syntax for sql-server, but it doesn't look like that works for our configuration. Here's my query:

SELECT r.rule_id as RULE_ID, 
LISTAGG(a.ATTRIBUTE_ID, ', ') WITHIN GROUP (ORDER BY a.ATTRIBUTE_ID) "ATTR_IDS"
FROM N_RULE r, N_ATTRIBUTE a 
WHERE r.RULE_ID = a.RULE_ID 
ORDER BY r.AUDIENCE, UPPER(r.NAME);

Answer 1

I think for your query to work, you need to add a group by, change the order by. You should also use proper explicit join syntax:

SELECT r.rule_id as RULE_ID, 
       LISTAGG(a.ATTRIBUTE_ID, ', ') WITHIN GROUP (ORDER BY a.ATTRIBUTE_ID) as "ATTR_IDS"
FROM N_RULE r JOIN
     N_ATTRIBUTE a 
     ON r.RULE_ID = a.RULE_ID 
GROUP BY r.rule_id
ORDER BY r.rule_id;

Or, possibly you want to include other attribute in the results:

SELECT r.rule_id, r.AUDIENCE, UPPER(r.NAME) 
       LISTAGG(a.ATTRIBUTE_ID, ', ') WITHIN GROUP (ORDER BY a.ATTRIBUTE_ID) as "ATTR_IDS"
FROM N_RULE r JOIN
     N_ATTRIBUTE a 
     ON r.RULE_ID = a.RULE_ID 
GROUP BY r.rule_id, r.AUDIENCE, UPPER(r.NAME)
ORDER BY r.AUDIENCE, UPPER(r.NAME);