Oracle/PLSQL: ORA-00975 Error

Error:

ORA-00975: date + date not allowed

Cause:

You tried to add two dates together. This is not allowed. You can only add numeric values to dates.

Action:

The options to resolve this Oracle error are:

Re-write your expression so that a numeric value is added to the date.

For example, if you tried to execute the following SQL statement:

SELECT sysdate + sysdate
FROM dual;

You would receive the following error message:

You could correct this error by substituting one date with a numeric value such as:

SELECT sysdate + 365
FROM dual;