Hierarchický dotaz

[Michal Zaschke]

Vytazeno z manualu - doufam, ze pomuze...

The LEVEL Pseudocolumn

SELECT statements that perform hierarchical queries can use the LEVEL
pseudocolumn. LEVEL returns the value 1 for a root node, 2 for a child
node of a root
node, 3 for a grandchild, etc. For more information on LEVEL, see the
section "Pseudocolumns". 

The number of levels returned by a hierarchical query may be limited by
available user memory. 

The following statement is similar to the first one, except that it uses
the LEVEL pseudocolumn to select only the first two levels of the
management hierarchy: 

SELECT LPAD(' ',2*(LEVEL-1)) || ename org_chart, 
empno, mgr, job 
    FROM emp 
    START WITH job = 'PRESIDENT' 
    CONNECT BY PRIOR empno = mgr AND LEVEL <= 2; 

ORG_CHART    EMPNO      MGR        JOB
------------ ---------- ---------- ---------
KING               7839            PRESIDENT
  JONES            7566       7839 MANAGER
  BLAKE            7698       7839 MANAGER
  CLARK            7782       7839 MANAGER




Vladimir Naprstek píše:
> 
> Zdravím,
> 
> lze hierarchický dotaz (Oracle) omezit na úrovně, do kterých až se má
> hrabat?
> Zatím jsem v dokumentaci nic nenašel...
> --
> Vladimír Náprstek       e-mail: vladimir.naprstek na prodeco.cz

-- 
 Ing. Michal Zaschke           
   DB Administrator             
Sokolovska uhelna, a.s.
phone: +420-168-465417
e-mail: zaschke na suas.cz