rundate problem

[yyy]

Hi, :cool:

I'm writing this query:

SELECT REASON_CODE
FROM REASON
WHERE
to_char(rundate,'MM/YYYY')
BETWEEN to_char(effective_from_date,'MM/YYYY')
AND to_char(effective_to_date,'MM/YYYY')

It gives me the error:
"RUNDATE": invalid identifier

Does someone knows what's the problem??? :confused: