select count(*)  from  (  
 select DNAorderno,Order_no,LTime,Settledate,Pay_fee,Commimission,Tel,order_Status,Order_Type 
 from(select b.orderno DNAorderno,a.order_no,a.add_time as LTime,b.settledate,a.pay_fee,null as Commimission,Tel,order_Status,Order_Type  from  ercp_t_order a 
 left join ercp_payresult b on a.order_no=b.reference where a.pay_id=5 and a.pay_status=1 ) 
 where ( LTime >='2012-02-19 00:00:00.000' and LTime<='2012-03-19 23:59:59.999' and   1=1   )  )  t 

select count(*)  from  (  
   select DNAorderno,
          Order_no,
          LTime,
          Settledate,
          Pay_fee,
          Commimission,
          Tel,
          order_Status,
          Order_Type
   from(select b.orderno 
               DNAorderno,
               a.order_no,
               a.add_time as LTime,
               b.settledate,
               a.pay_fee,null as Commimission,
               Tel,order_Status,
               Order_Type  
        from  ercp_t_order a 
        left join ercp_payresult b on a.order_no=b.reference 
        where a.pay_id=5 and a.pay_status=1 
       ) test
 
   where test.LTime >=to_date('2012-02-19 00:00:00.000','你需要的日期格式') and test.LTime<=to_date('2012-03-19 23:59:59.999','你需要的日期格式') and   1=1  
)  t

------解决方案--------------------
 to_timestamp('2012-02-19 00:00:00.000','yyyy-mm-dd hh24:mi:ss.ff3')