Cómo utilizar alias en la cláusula Dónde?
-
27-09-2019 - |
Pregunta
Tengo este procedimiento:
PROCEDURE P_LOAD_EXPIRED_ACCOUNT
(
pDayDiff IN NUMBER,
ExpiredCur OUT MEGAGREEN_CUR
)
IS
BEGIN
OPEN ExpiredCur FOR
SELECT
ACCOUNT_NAME, SERVICE_TYPE,
CASE
WHEN SERVICE_TYPE = 1 THEN ADD_MONTHS(ACTIVATED_DATE,3)
WHEN SERVICE_TYPE = 2 THEN ADD_MONTHS(ACTIVATED_DATE,6)
WHEN SERVICE_TYPE = 3 THEN ADD_MONTHS(ACTIVATED_DATE,12)
END
AS EXPIRED_DATE
FROM SUBSCRIBERS
WHERE (EXPIRED_DATE - CURRENT_DATE) < pDayDiff;
END;
pero SQL Developer genera este error:
Error (20,10): PL / SQL: ORA-00904: "EXPIRED_DATE": inválido identificador
Creo que PLSQL me permite usar alias en la cláusula WHERE, pero ¿hay algo que olvide?
Gracias de antemano.
Solución
No se puede hacer referencia al alias de columna en la cláusula WHERE - sus opciones son:
- replicar la instrucción CASE en la cláusula WHERE
-
utilizar una subconsulta:
PROCEDURE P_LOAD_EXPIRED_ACCOUNT(pDayDiff NUMBER, ExpiredCur OUT MEGAGREEN_CUR) IS BEGIN OPEN ExpiredCur FOR SELECT x.account_name, x.service_type, x.expired_date FROM (SELECT s.account_name, s.service_type, CASE WHEN s.service_type = 1 THEN ADD_MONTHS(ACTIVATED_DATE,3) WHEN s.service_type = 2 THEN ADD_MONTHS(ACTIVATED_DATE,6) WHEN s.service_type = 3 THEN ADD_MONTHS(ACTIVATED_DATE,12) END AS EXPIRED_DATE FROM SUBSCRIBERS s) x WHERE x.expired_date - CURRENT_DATE < pDayDiff; END;
Oracle 9i +
WITH summary AS ( SELECT s.account_name, s.service_type, CASE WHEN s.service_type = 1 THEN ADD_MONTHS(ACTIVATED_DATE,3) WHEN s.service_type = 2 THEN ADD_MONTHS(ACTIVATED_DATE,6) WHEN s.service_type = 3 THEN ADD_MONTHS(ACTIVATED_DATE,12) END AS EXPIRED_DATE FROM SUBSCRIBERS s) SELECT x.account_name, x.service_type, x.expired_date FROM summary x WHERE x.expired_date - CURRENT_DATE < pDayDiff;
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