Fetching records greater then datetime does not work in c# windows service application

Question

Hi All,

I have the following queries (both are for same purpose) which fetches records greater the the datetime column.

SELECT PROSPECT.BUSINESS_UNIT,PROSPECT.LAST_CHANGED FROM  PROSPECT WHERE (TO_CHAR(LAST_CHANGED, 'YYYY-MM-DD HH24:MI:SS') > (SELECT TO_CHAR(LAST_UPDATED, 'YYYY-MM-DD HH24:MI:SS') FROM LAST_UPDATE))


SELECT PROSPECT.BUSINESS_UNIT,PROSPECT.LAST_CHANGED FROM  PROSPECT WHERE LAST_CHANGED > (SELECT LAST_UPDATED FROM LAST_UPDATE))


This query works fine in query window and also in the windows console application. But the same query does not work from c# Application.  Could any one has any idea why this behaves differently in c# windows service application.

Regards
Venkatesh G