CREATE CURSOR test (id I, iparent I, ilevel i)
INSERT INTO test (id , iparent , ilevel) VALUES (13, 0, 0) 
INSERT INTO test (id , iparent , ilevel) VALUES (15,13,1) 
INSERT INTO test (id , iparent , ilevel) VALUES (25,15,3) 
INSERT INTO test (id , iparent , ilevel) VALUES (26,15,2) 
INSERT INTO test (id , iparent , ilevel) VALUES (30,25,2) 
INSERT INTO test (id , iparent , ilevel) VALUES (41,0,0)

DO WHILE !EMPTY(iparent) AND SEEK(iparent ...)

CREATE CURSOR test (ID I, iparent I)
INSERT INTO test (ID, iparent) VALUES (13, 0)
INSERT INTO test (ID, iparent) VALUES (15,13)
INSERT INTO test (ID, iparent) VALUES (25,15)
INSERT INTO test (ID, iparent) VALUES (26,15)
INSERT INTO test (ID, iparent) VALUES (30,25)
INSERT INTO test (ID, iparent) VALUES (41, 0)

INDEX ON ID TAG ID
INDEX ON iparent TAG iparent

CREATE CURSOR result (ID I, iparent I, ilevel I)
INDEX ON ID TAG ID
INDEX ON ilevel TAG ilevel
SET ORDER TO
* Get roots
INSERT INTO result (ID, iparent, ilevel) ;
  SELECT ID, iparent, 0 FROM test WHERE iparent = 0

* Get levels
lnLevel = 1
DO WHILE _TALLY > 0
  INSERT INTO result (ID, iparent, ilevel) ;
    SELECT test.ID, test.iparent, m.lnLevel ;
    FROM test ;
    WHERE test.iparent IN (SELECT ID FROM result ;
    WHERE result.ilevel = m.lnLevel - 1) ;
    AND test.ID NOT IN (SELECT ID FROM result)
  lnLevel = m.lnLevel + 1
ENDDO
BROWSE