consulta sql

[camilop24]

para los magos de sql:
teniendo en cuenta esta tabla:
CREATE TABLE empleado(
a NUMBER(10) PRIMARY KEY,
b NUMBER(10) REFERENCES empleado,
c NUMBER(10) REFERENCES empleado
);

que hace esta consulta?

SELECT KONNECT_BY_ROOT a AS raiz,
a, b, LEVEL AS posicion,
SUBSTR(SYS_KONNECT_BY_PATH(a,'-'),2) AS ruta
FROM sade_adu
START WITH b IS NULL
KONNECT BY PRIOR a=b
UNION
SELECT KONNECT_BY_ROOT a AS raiz,
a, c, LEVEL AS posicion,
SUBSTR(SYS_KONNECT_BY_PATH(a,'-'),2) AS ruta
FROM sade_adu
START WITH c IS NULL
KONNECT BY PRIOR a=c;

porfa cambien la k por la c, en la palabra connect,