ORA-22902 CURSOR expression not allowed Error Cause: CURSOR on a subquery..

Question

Hi,
I found same issue in a metalink thread which is addressed in Oracle 12.1 which doesn't help me now. I need to rewrite the below query. Does anyone have any suggestions how to go about it?
thanks,
April
working in Oracle 11.2.0.3.1, windows server, doing an upgrade from 10g to 11g. Piece of code is failing with following error via TOAD
Oracle Database Error Code ORA-22902 Description :
CURSOR expression not allowed
Error Cause:
CURSOR on a subquery is allowed only in the top-level SELECT list of a query.
The below code is returning a tree of data for projects, units within the buildings.
Code as follows:
SELECT LEVEL
, p.project_id
|| NVL (p.file_ref, ' ')
|| '] ['
|| NVL (p.project_ref, ' ')
|| '] '
|| p.project_name
|| ' ( '
|| (SELECT COUNT (*)
FROM PROJECT p1
WHERE p1.parent_project_id = p.project_id)
|| ' sub-projects, '
|| (SELECT COUNT (*)
FROM PROJECT_ELEMENT pe2
WHERE pe2.project_id = p.project_id)
|| ' elements)' AS project_description
CURSOR
(SELECT pe.element_id
|| pe.element_ref
|| '] '
|| pe.element_name
|| ' ('
|| pe.unit_count
|| ')' AS element_description
CURSOR
(SELECT hu.hu_id
|| hu.hu_ref
|| '] '
|| CASE
WHEN hu.bedroom_count IS NOT NULL
THEN ', Bedrooms: ' || hu.bedroom_count
ELSE NULL
END
|| CASE
WHEN hu.bedspace_count IS NOT NULL
THEN ', Bedspaces: ' || hu.bedspace_count
ELSE NULL
END AS hu_descripton
FROM HOUSING_UNIT hu
WHERE hu.element_id = pe.element_id
ORDER BY hu.hu_ref
) AS housing_units
FROM PROJECT_ELEMENT pe
WHERE pe.project_id = p.project_id
ORDER BY pe.element_ref, pe.element_name
) elements
FROM PROJECT p
START WITH p.project_id = l_root_project_id
CONNECT BY PRIOR p.project_id = p.parent_project_id -- connect by used with LEVEL keyword
ORDER SIBLINGS BY p.file_ref DESC
, p.project_ref DESC
, p.project_name DESC;
Edited by: AprilM on Jul 17, 2012 10:28 AM

Answer 1

Interesting. I am getting even worse results on 11.2.0.1.0:
SQL> select * from v$version
  2  /
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE    11.2.0.1.0      Production
TNS for 32-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
SQL> select dname,cursor(select ename from emp e where e.deptno = d.deptno) from dept d
  2  /
select dname,cursor(select ename from emp e where e.deptno = d.deptno) from dept d
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-00905: missing keyword
SQL> connect scott
Enter password: *****
Connected.
SQL> select * from v$version
  2  /
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Prod
PL/SQL Release 10.2.0.4.0 - Production
CORE    10.2.0.4.0      Production
TNS for 32-bit Windows: Version 10.2.0.4.0 - Production
NLSRTL Version 10.2.0.4.0 - Production
SQL> select dname,cursor(select ename from emp e where e.deptno = d.deptno) from dept d
  2  /
DNAME          CURSOR(SELECTENAMEFR
ACCOUNTING     CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
CLARK
KING
MILLER
RESEARCH       CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
SMITH
JONES
SCOTT
ADAMS
FORD
SALES          CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
ALLEN
WARD
MARTIN
BLAKE
TURNER
JAMES
6 rows selected.
OPERATIONS     CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
no rows selected
SQL> And double CURSOR also works fine in 10g:
SQL> select cursor(select dname,cursor(select ename from emp e where e.deptno = d.deptno) from dept d) from dual
  2  /
CURSOR(SELECTDNAME,C
CURSOR STATEMENT : 1
CURSOR STATEMENT : 1
DNAME          CURSOR(SELECTENAMEFR
ACCOUNTING     CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
CLARK
KING
MILLER
RESEARCH       CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
SMITH
JONES
SCOTT
ADAMS
FORD
SALES          CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
ENAME
ALLEN
WARD
MARTIN
BLAKE
TURNER
JAMES
6 rows selected.
OPERATIONS     CURSOR STATEMENT : 2
CURSOR STATEMENT : 2
no rows selectedSY.
Edited by: Solomon Yakobson on Jul 17, 2012 1:27 PM