How to check if your DB is open using spfile or pfile

If your DB is open using pfile:

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SELECT DECODE(value, NULL, 'PFILE', 'SPFILE') "Init File Type" 

   FROM sys.v_$parameter WHERE name = 'spfile';

--- PFILE

If your DB is open using SPFILE:

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SELECT DECODE(value, NULL, 'PFILE', 'SPFILE') "Init File Type" 

   FROM sys.v_$parameter WHERE name = 'spfile';

--SPFILE