Comment utiliser une colonne calculée dans l'état où?

Question

Comment utiliser une colonne calculée dans la condition where dans Oracle 9i?

Je veux utiliser quelque chose comme

select decode (:pValue,1, 
       select sysdate from dual, 
       select activation_date from account where AcNo = 1234) as calDate 
where caldate between startDate and endDate; 

Answer 1

Vous pouvez utiliser une vue en ligne:

select calcdate from 
(
select startDate, endDate, 
     decode (:pValue,1, 
       select sysdate from dual, 
       select activation_date from account where AcNo = 1234) as calcdate 
) 
where calcdate between startDate and endDate; 

Answer 2

Vous pouvez sélectionner votre date de double et rejoindre les résultats:

select * 
from <<your table with startDate and endDate columns>> -- Since you ommited the main "from" clause from your statement 
,  (
     select decode(:pValue 
         , 1, sysdate 
         , (select activation_date from account where AcNo = 1234) 
        ) as calDate 
     from dual 
     ) c 
where c.calDate between startDate and endDate 
... -- any other conditions you may need