Está comprobando cadenas contra una cadena vacía, por lo que tiene problemas; en Oracle, es mejor que verifique si su cadena is not null :
SELECT CASE WHEN '7C54D3E133830A78E040A8C010014B7D' is not null
THEN '7C54D3E133830A78E040A8C010014B7D'
WHEN 'e84a4433966c4b8996ce34905acff63d' is not null
THEN 'e84a4433966c4b8996ce34905acff63d'
WHEN '7faa9126b1c6412fa58375ab2b2be1db' is not null
THEN '7faa9126b1c6412fa58375ab2b2be1db'
ELSE NULL
END
FROM DUAL
Acerca de la forma en que Oracle trata la cadena vacía y el valor nulo, aquí encuentras algo más
Un ejemplo:
select q'['' = '']' , case when '' = '' then 'YES' else 'NO' end from dual union all
select q'['' is null]' , case when '' is null then 'YES' else 'NO' end from dual union all
select q'['' = null ]' , case when '' = null then 'YES' else 'NO' end from dual union all
select q'[null = null]' , case when null = null then 'YES' else 'NO' end from dual union all
select q'[null is null]' , case when null is null then 'YES' else 'NO' end from dual union all
select q'['' != '']' , case when '' != '' then 'YES' else 'NO' end from dual union all
select q'['' is not null]' , case when '' is not null then 'YES' else 'NO' end from dual union all
select q'['' != null ]' , case when '' != null then 'YES' else 'NO' end from dual union all
select q'[null != null]' , case when null != null then 'YES' else 'NO' end from dual union all
select q'[null is not null]', case when null is not null then 'YES' else 'NO' end from dual
da:
'' = '' NO
'' is null YES
'' = null NO
null = null NO
null is null YES
'' != '' NO
'' is not null NO
'' != null NO
null != null NO
null is not null NO
En una palabra, la única verificación en la que puede confiar cuando se habla de NULL , es:IS [NOT] NULL
