Oracle Error PLS-00618: type mismatch found at ‘string’ between operands in a NULLIF expression

Oracle Error Message

PLS-00618: type mismatch found at ‘string’ between operands in a NULLIF expression

Reason for the Error

In a NULLIF expression, the two operands do not match in datatype, and it is unclear which implicit conversion is required to correct the mismatch.

Solution

Change the operands so that their datatypes match. Consider using datatype conversion functions in the operands.