Question

I have a hierarchical query in Oracle 10 SQL that used to work. However, I removed the materialized view it was based on, and now I can’t get it to come out properly, even leaving that view out altogether.

The original query looked like this:

select oh.name, oh.description
  , sys_connect_by_path(groupname, ':') "Groups"
  , (select count(*) 
      from ml.lastobsmv 
      where lastobsmv.hdid = oh.hdid) as obscount
from ml.obshead oh
  join ml.hiergrps hg on oh.groupid = hg.groupid
    connect by prior hg.groupid = hg.parentid

I presume it still works, but without the lastobsmv view, I can’t test it.

If I trim it down to

select oh.name, oh.description
from  ml.obshead oh
  join ml.hiergrps hg on oh.groupid = hg.groupid

it still works, returning 41K records. However, when I use the connect by clause, it goes out of control, returning millions of records (I usually have to cancel it before getting an accurate count).

select oh.name, oh.description
  , sys_connect_by_path(groupname, ':') "Groups"
from ml.obshead oh
  join ml.hiergrps hg on oh.groupid = hg.groupid
    connect by prior hg.groupid = hg.parentid

Am I missing something really blatant here, or am I misunderstanding the way this is supposed to work? Thanks.

---

Vadim,

It should return a list of Observation Terms along with the group they’re in. For example,

Obshead:

# CYCLE DAYS, number of days in menstrual cycle, 100

HierGrps:

100, 50, Gynecology
50, 10, Tx
10, 0, Basic

should produce

# CYCLE DAYS, number of days in menstrual cycle, :Basic:Tx:Gynecology

(eventually along with the number of times this obs term has been used, but I’ll worry about that later).

Answer 1

select
    oh.name,
    oh.description,
    hg."Groups"
from
    obshead oh
    join ( select
               groupid,
               sys_connect_by_path( groupname, ':' ) "Groups"
           from
               hiergrps
           start with
               parentid = 0
           connect by
               prior groupid = parentid
         ) hg
      on oh.groupid = hg.groupid

Here’s the sample data I’ve used to test the query:

create table obshead
( name varchar2(30)
, description varchar2(30)
, groupid number(3)
);
insert into obshead ( name, description, groupid )
     select 'Name One', 'Description One', 100 from dual union all
     select 'Name Two', 'Description Two', 200 from dual
;

create table hiergrps
( groupid number(3)
, parentid number(3)
, groupname varchar2(30)
);
insert into hiergrps ( groupid, parentid, groupname )
     select 100, 50, 'Gynecology' from dual union all
     select  50, 10, 'Tx'         from dual union all
     select  10,  0, 'Basic'      from dual
;