I can't understand the usage of the using word. Can you explain me?
SELECT 1
FROM CONF_RAGGR_OPZTAR ropt
JOIN TAR_OPZIONI_TARIFFARIE OPT using (OPT_OPZIONE_TARIFFARIA_ID)
JOIN CONF_RAGGRUPPAMENTI_FORN rgf using (RGF_RAGGRUPPAMENTO_FORN_ID)
JOIN CONF_FORNITURE_REL_RAGG forg using (RGF_RAGGRUPPAMENTO_FORN_ID)
JOIN CONF_FORNITURE forn using (FORN_FORNITURA_ID)
LEFT JOIN (
select *
from CONF_ELEMENTI_FATTURABILI
where ELF_FLAG_ANN = 'N'
AND ELF_DATA_VER_FIN = TO_DATE('31/12/9999','DD/MM/YYYY')
) elf **using** (ROPT_RAGGR_OPZTAR_ID,COID_CONTRATTUARIO_ID,ROPT_DATA_INI,EDW_PARTITION)
-- LEFT OUTER JOIN TAR_VOCI_FATTURABILI vof
-- ON (elf.VOF_VOCE_FATTURABILE_ID = vof.VOF_VOCE_FATTURABILE_ID)
-- LEFT OUTER JOIN BASE_FASCE_ORARIE fas
-- ON (fas.FAS_FASCIA_ORARIA_ID = elf.FAS_FASCIA_ORARIA_ID)
WHERE FORN_FORNITURA_ID = 'QJlXmOFZPF3eAlAG'
ORDER BY elf.ELF_VERSIONE DESC;
The using
keyword indicates that this is a natural join. This means that the column names on both side of the join are identical.
In your case this means that you will join both sides on ROPT_RAGGR_OPZTAR_ID
, COID_CONTRATTUARIO_ID
, ROPT_DATA_INI
and EDW_PARTITION
.