Analytic Functions in CONNECT BY Queries

Question

Can analytic functions be used in a CONNECT BY query? Are there limits?
This problem occurs in Oracle 11.1.0.6.0, 10.2 and 10.1.
Here is the presenting problem:
Starting with data like this:
CREATE TABLE     enrollment
(      name          VARCHAR2 (10)
,      coursenumber     NUMBER
INSERT INTO enrollment (name, coursenumber) VALUES ('Ted',      101);
INSERT INTO enrollment (name, coursenumber) VALUES ('Ted',      102);
INSERT INTO enrollment (name, coursenumber) VALUES ('Ted',      103);
INSERT INTO enrollment (name, coursenumber) VALUES ('Mary',      102);
INSERT INTO enrollment (name, coursenumber) VALUES ('Mary',      104);
INSERT INTO enrollment (name, coursenumber) VALUES ('Hiro',      101);
INSERT INTO enrollment (name, coursenumber) VALUES ('Hiro',      104);
INSERT INTO enrollment (name, coursenumber) VALUES ('Hiro',      105);
COMMIT;I'm trying to get cross-tab output like this:
NAME       TXT
Hiro         101            104  105
Mary              102       104
Ted          101  102  103without knowing before-hand what course numbers, or even how many course numbers, will be in the results.
My strategy was to use LPAD to make the course numbers always occupy 5 spaces.
If n "columns" needed to be left blank before the number, I wanted to add 5n extra spaces.
I tried this:
WITH     universe     AS
     SELECT     name
     ,     coursenumber
     ,     DENSE_RANK () OVER ( ORDER BY        coursenumber)     AS cnum
     ,     ROW_NUMBER () OVER ( PARTITION BY  name
                               ORDER BY          coursenumber
                       )                         AS snum
     FROM     enrollment
SELECT     name
,     REPLACE ( SYS_CONNECT_BY_PATH ( LPAD ( TO_CHAR (coursenumber)
                                          , 5 * (cnum - LAG (cnum, 1, 0)
                                                               OVER ( PARTITION BY  name
                                                                         ORDER BY          coursenumber
          )     AS txt
FROM     universe
WHERE     CONNECT_BY_ISLEAF     = 1
START WITH     snum     = 1
CONNECT BY     snum     = PRIOR snum + 1
AND          name     = PRIOR name
ORDER BY     name
;but the txt column was always NULL.
I tried showing some of the intermediate calculations:
WITH     universe     AS
     SELECT     name
     ,     coursenumber
     ,     DENSE_RANK () OVER ( ORDER BY        coursenumber)     AS cnum
     ,     ROW_NUMBER () OVER ( PARTITION BY  name
                               ORDER BY          coursenumber
                       )                         AS snum
     FROM     enrollment
SELECT     name
,     REPLACE ( SYS_CONNECT_BY_PATH ( LPAD ( TO_CHAR (coursenumber)
                                          , 5 * (cnum - LAG (cnum, 1, 0)
                                                               OVER ( PARTITION BY  name
                                                                         ORDER BY          coursenumber
          )     AS txt
,     coursenumber
,     cnum
,     LAG (cnum, 1, 0) OVER ( PARTITION BY  name
                                            ORDER BY          coursenumber
                     )      AS lag_cnum
FROM     universe
-- WHERE     CONNECT_BY_ISLEAF     = 1
START WITH     snum     = 1
CONNECT BY     snum     = PRIOR snum + 1
AND          name     = PRIOR name
ORDER BY     name
;and they all seemed reasonable:
NAME       TXT                            COURSENUMBER       CNUM   LAG_CNUM
Hiro                                               101          1          0
Hiro                                               104          4          1
Hiro                                               105          5          4
Mary                                               102          2          0
Mary                                               104          4          2
Ted                                                101          1          0
Ted                                                102          2          1
Ted                                                103          3          2but txt was still NULL.
I got around the problem by computing the LAG in a sub-query (see [this thread|http://forums.oracle.com/forums/message.jspa?messageID=3875566#3875566]), but I'd like to know why LAG didn't work in the CONNECT BY query, or at least within SYS_CONNECT_BY_PATH.
I've had other problems before trying to use analytic functions in CONNECT BY queries. Sometimes, the presence of an analytic function woudl cause CONNECT BY to never work, sometimes it would destroy the order of the output. (Sorry, I don't have those examples handy now.)
Are there limitations on using analytic functions in a CONNECT BY query?
is there a work-around other than computing the analytic functions in a sub-query?
Thanks.

Answer 1

how about
SQL> with temp as
  2  (select name
  3       , coursenumber
  4    from enrollment
  5  )
  6  , courses as
  7  (select distinct
  8          coursenumber
  9     from enrollment
10  )
11  select name
12       , replace (sys_connect_by_path (case when t_course is not null
13         then rpad (t_course, 8, ' ')
14         else rpad (' ', 8, ' ')
15         end, ';'), ';', ' ') scbp
16    from (
17  select t.name
18       , t.coursenumber t_course
19       , c.coursenumber c_course
20       , row_number() over (partition by t.name
21                                order by c.coursenumber
22                           ) rn
23    from temp  t partition by (name)
24    right outer
25    join courses c
26      on c.coursenumber = t.coursenumber
27  )
28   where connect_by_isleaf = 1
29   start with rn = 1
30   connect by rn = prior rn + 1
31   and name = prior name;
NAME       SCBP
Hiro        101                        104      105
Mary                 102               104
Ted         101      102      103