oracle data base error ORA-00920 invalid relational operator

This is my code after check syntax this error appear

ORA-00920 invalid relational operator

select id,  classification
from  Closerfprfx
where classification in ('xxx','RFX','aa') and region('e','sdfsdf','dfg') 

What problem on this code?

Answer

Unless you have a function called region that accepts three string arguments, this code does not make sense:

region('e','sdfsdf','dfg') 

I assume that you are missing the in:

 region in ('e', 'sdfsdf', 'dfg')