Case sensitivity? (collaction/Oracle case sensitivity)

Mix of datatypes? trim(x)=:comp -> characters? :comp=0 -> number?

Why is the trim added in the last line?

You have supplier_country = receiver_country and :ccty = 0 (without trim)

and then suddenly trim(supplier_country) = :ccty and trim(receiver_country) = :ccty

-> supplier_country = receiver_country and supplier_country=trim(:ccty) ?