The following query:
select cdate from rprt where cdate <= TO_CHAR(sysdate, \'YYYY/MM/DD-HH24-MI-SS-SSSSS\') and ryg=\'R\' and cnum=\'C002\';
Convert Timestamp to Date as mentioned below, it will work for sure -
select TO_DATE(TO_CHAR(TO_TIMESTAMP ('2015-04-15 18:00:22.000', 'YYYY-MM-DD HH24:MI:SS.FF'),'MM/DD/YYYY HH24:MI:SS'),'MM/DD/YYYY HH24:MI:SS') dt from dual