Connect by prior by speific order problem.

Question

Oracle: 10.2.0.4
I have a table containing events backup.
i want to list the hierarchy within that backup oreder by the time_stamp for all levels.
create table BCK_EVENTS
  bck_backup_id           NUMBER(9) default 0 not null,
  event_id                   NUMBER(15) default 0 not null,
  event_name              NVARCHAR2(100) default ' ' not null
  time_stamp               NUMBER(9) default 0 not null,
  parent_event            NUMBER(15) default 0 not null,
add constraint BCK_EVENTS_PK primary key (BCK_EVENT_ID, EVENT_ID); // event_id is not unique can be under one or more backup id'sthis is not a tree with one root, there is more than one event in the root level (level 1).
example:
Event Name      Time         level   <- time is numeric but for easier reading.
*Event A          10:00         1
   *Event C        10:30         2
     *Event B      11:17         3
*Event H          12:10         1
     *Event J       12:10         2
     *Event M      12:21         2
*Event Z          15:33         1
   *Event R        16:56          2
    *Event M      16:57          3
   *Event G        20:20         2What i tried was :
select  lpad( '*', level*2 ) || event_id,event_name,time_stamp,parent_event,level from bck_events
     where bck_event_id=100031
     start with parent_event is null
    connect by prior event_id = parent_eventand there are two problems with it.
1. it's not ordered even when i added an Index (parent_event,time_stamp) and try to hint it.
2. it returns loads of multiple rows.
hope it's clear enough. I thank for any help.
Edited by: 973065 on Nov 25, 2012 8:04 AM
Edited by: 973065 on Nov 25, 2012 9:23 AM
Edited by: 973065 on Nov 25, 2012 9:29 AM
Edited by: 973065 on Nov 25, 2012 9:31 AM

Answer 1

Hi,
973065 wrote:
Oracle: 10.2
I have a table containing events backup.
i want to list the hierarchy within that backup oreder by the time_stamp for all levels.
create table BCK_EVENTS
bck_backup_id           NUMBER(9) default 0 not null,
event_id                   NUMBER(15) default 0 not null,
event_name              NVARCHAR2(100) default ' ' not null
time_stamp               NUMBER(9) default 0 not null,
parent_event            NUMBER(15) default 0 not null,
Thanks for posting the version number and the CREATE TABLE statement. Don't forget to post INSERT statements for your sample data.
add constraint BCK_EVENTS_PK primary key (BCK_EVENT_ID, EVENT_ID); // event_id is not unique can be under one or more backup id's
this is not a tree with one root, there is more than one event in the root level (level 1).Is it a forest, that is, a set of trees?
example:
Event Name      Time         level   <- time is numeric but for easier reading.
*Event A          10:00         1
*Event C        10:30         2
*Event B      11:17         3
*Event H          12:10         1
*Event J       12:10         2
*Event M      12:21         2
*Event Z          15:33         1
*Event R        16:56          2
*Event M      16:57          3
*Event G        20:20         2
That seems to be a forest, that is, every row has 0 or 1 parent, and no row is its own ancestor.
What i tried was :
select lpad( '*', level*2 ) || event_id,event_name,time_stamp,parent_event,level from bck_events
where bck_event_id=100031
start with parent_event is null
connect by prior event_id = parent_event
and there are two problems with it.
1. it's not ordered even when i added an Index (parent_event,time_stamp) and try to hint it.Depending on your data, you may just need to add
ORDER SIBLINGS BY  time_stampat the end, after the CONNECT BY clause.
If you need rows sorted by time_stamp under their roots, but otherwise without regard to the hierarchy, then use CONNECT_BY_ROOT.
2. it returns loads of multiple rows.Again, it depends on your data. I'll bet you need something more in the CONNECT BY clause, but I can't tell what without some sample data and an exxplanation of how you gett the results you posted from that data. The fact that bck_event_id is part of the primary key makes me suspect that maybe bck_event_id needs to be somewhere in the CONNECT BY clause, but that's just a wild guess.
hope it's clear enough. I thank for any help.As mentioned before, see the forum FAQ {message:id=9360002}