oracle如何比较时间？

1、
select  t1.DEVICE_NAME ,t2.MONITOR_NAME,t3.OBJECTNAME,t3.SAMPLENAME,t3.SAMPLETIME  from T_DEVICE t1,T_MONITOR t2,T_SAMPLES t3 where t1.DEVICE_ID=t2.DEVICE_ID and t2.MONITOR_ID=t3.MONITOR_ID 
and  t3.SAMPLETIME <sysdate order by t1.DEVICE_NAME
2、
select  t1.DEVICE_NAME ,t2.MONITOR_NAME,t3.OBJECTNAME,t3.SAMPLENAME,t3.SAMPLETIME  from T_DEVICE t1,T_MONITOR t2,T_SAMPLES t3 where t1.DEVICE_ID=t2.DEVICE_ID and t2.MONITOR_ID=t3.MONITOR_ID 
and  t3.SAMPLETIME <21-九月 -2009 05:19:04 PM order by t1.DEVICE_NAME

1语句执行没问题，2语句执行说什么索引中丢失in或out 参数 ，  请各位指点一下！ 究竟要如何去比较oracle时间

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21-九月 -2009 05:19:04 PM
-->转换下
to_date('21-九月 -2009 05:19:04 PM','yyyy-mm-dd hh24:mi:ss')

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21-九月 -2009 05:19:04 PM
处理为标准时间格式
'yyyy-mm-dd hh24:mi:ss'

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引用

1、
select  t1.DEVICE_NAME ,t2.MONITOR_NAME,t3.OBJECTNAME,t3.SAMPLENAME,t3.SAMPLETIME  from T_DEVICE t1,T_MONITOR t2,T_SAMPLES t3 where t1.DEVICE_ID=t2.DEVICE_ID and t2.MONITOR_ID=t3.MONITOR_ID 
and  t3.SAMPLETIME <sysdateorder by t1.DEVICE_NAME
2、
select  t1.DEVICE_NAME ,t2.MONITOR_NAME,t3.OBJECTNAME,t3.SAMPLENAME,t3.SAMPLETIME  from T_DEVICE t1,T_MONITOR t2,T_SAMPLES t3 where t1.DEVICE_ID=t2.DEVICE_ID and t2.MONITOR_ID=t3.MON