NVL函數在子查詢

Question

我有以下查詢：

select E.EQUIPMENT_GID, NVL((SELECT SUBSTR(ES.STATUS_VALUE_GID,INSTR(ES.STATUS_VALUE_GID, '.')+1) FROM EQUIPMENT_STATUS ES WHERE ES.EQUIPMENT_GID=E.EQUIPMENT_GID 
AND ES.STATUS_TYPE_GID LIKE '%EQUIPMENT_STATUS' AND ROWNUM=1),'ZZZ') AS E_STATUS, NVL((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID 
AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' and rownum=1),'ZZZ') AS PERM_DISTRICT_REF, 'PSKL-'||REPLACE(SUBSTR((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF 
WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' AND ROWNUM=1),(INSTR((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF 
WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' AND ROWNUM=1), '.',1,1) +1) ), ' PERMANENT DISTRICT','') AS DISTRICT_PSKL_XID, 
**SUBSTR(E.PARK_LOCATION_GID,5,11) AS PARK_LOCATION_GID** FROM EQUIPMENT E 
WHERE E.EQUIPMENT_GID=? 

現在我想檢查空值，在我的子查詢與「ZZZ」取代他們SUBSTR(E.PARK_LOCATION_GID,5,11) AS PARK_LOCATION_GID

任何一個能提出解決方案到這一個。如果您使用的是SQL

Answer 1

我得到了它，它應該是：

select E.EQUIPMENT_GID, NVL((SELECT SUBSTR(ES.STATUS_VALUE_GID,INSTR(ES.STATUS_VALUE_GID, '.')+1) FROM EQUIPMENT_STATUS ES WHERE ES.EQUIPMENT_GID=E.EQUIPMENT_GID 
AND ES.STATUS_TYPE_GID LIKE '%EQUIPMENT_STATUS' AND ROWNUM=1),'ZZZ') AS E_STATUS, NVL((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID 
AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' and rownum=1),'ZZZ') AS PERM_DISTRICT_REF, 'PSKL-'||REPLACE(SUBSTR((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF 
WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' AND ROWNUM=1),(INSTR((SELECT EREF.EQUIPMENT_REFNUM_QUAL_GID FROM EQUIPMENT_REFNUM EREF 
WHERE EREF.EQUIPMENT_GID = E.EQUIPMENT_GID AND EREF.EQUIPMENT_REFNUM_QUAL_GID LIKE '%PERMANENT DISTRICT%' AND ROWNUM=1), '.',1,1) +1) ), ' PERMANENT DISTRICT','') AS DISTRICT_PSKL_XID, 
NVL((SUBSTR(E.PARK_LOCATION_GID,5,11)),'ZZZ') AS PARK_LOCATION_GID** FROM EQUIPMENT E 
WHERE E.EQUIPMENT_GID=? 

Answer 2

試試這個：

SUBSTR(ISNULL(E.PARK_LOCATION_GID, 'zzz'),5,11) AS PARK_LOCATION_GID