Oracle Error PLS-00383: type mismatch found at ‘string’ inside an IN or NOT IN clause

Oracle Error Message

PLS-00383: type mismatch found at ‘string’ inside an IN or NOT IN clause

Reason for the Error

In a test for set membership such as X NOT IN (SELECT Y … ), the expressions X and Y do not match in datatype, and it is unclear which implicit conversion is required to correct the mismatch.

Solution

Change the expressions so that their datatypes match. You might want to use datatype conversion functions in the select list.