Complex SELECT IN doesn't work in Oracle 11 - sql

Question

I have this query:
SELECT d.CREATION_DATE, r.RN5, s.rn1, s.PI1, r.KTR,
VERSION_NR, getTitle(r.RN5, VERSION_NR) AS TITLE
FROM DOI_SNAPSHOT d, RELATION r, SOURCE_ADDRESS s
WHERE r.RN1 NOT IN (8010,777)
AND d.RN5 = r.RN5
AND r.RN1 = s.RN1
AND r.RN5 IN (91010008,91010015)
AND r.RN5 not in (
SELECT RN5
FROM RELATION
WHERE DOI5 IS NOT NULL
AND DOI_DATE IS NULL
)
AND VERSION_NR = (
SELECT max(VERSION_NR)
FROM DOI_SNAPSHOT dmax
WHERE d.RN5 = dmax.RN5
);
and this query:
SELECT substr(w.message, 5, instr(w.message, 'KTR') - 5) AS RN5
FROM WEB_STATISTICS w
WHERE w.ACTION = 'DOI Display'
GROUP BY substr(w.message, 5, instr(w.message, 'KTR') - 5)
ORDER BY count(*) DESC;
both of them are working correctly.
Now if I replace the first query's line
AND r.RN5 IN (91010008, 91010015)
and put in the parenthesis the second query, I get an error
ORA-00907: missing right parenthesis
00907. 00000 - "missing right parenthesis"
I don't know what is happening, since both queries are working oracle should at least accept the syntax?

Answer 1

The problem is that you have an order by clause in your second query, and you've left that in when you turned it into a subquery. The clause isn't valid in that context and makes no sense anyway - you're looking for members of a set, the ordering of the elements within that set is irrelevant - so you should remove the order by count(*) desc part.
To demonstrate with a simple but very contrived example; with an order by clause:
select * from dual
where dummy in (select 'X' from dual order by 1 desc);
SQL Error: ORA-00907: missing right parenthesis
00907. 00000 - "missing right parenthesis"
And without:
select * from dual
where dummy in (select 'X' from dual);
DUMMY
-----
X
As a simplistic explanation of the error message, when the parser see the order by it thinks that applies to the main query, and therefore the subquery should have already been terminated a closing right parenthesis - which is missing.
This is a message that often doesn't mean what you might think it implies - it isn't that the query overall has unbalanced parentheses, just that it's found a syntax error that may have been caused by a missing or misplaced one.

Answer 2

Generally error ORA-00907 usually means "there is a syntax error somewhere before this point".
Let's try
SQL> select * from dual
2 where dummy in (select dummy from dual);
DUMMY
-----
X
SQL> select * from dual
2 where dummy in (select dummy from dual order by 1);
ORA-00907: missing right parenthesis
So you should remove ORDER BY clause from inner query.