SQL & PL/SQL

I Have a query which will calculate the number of orders on 5 days range.and planning to run daily.

SELECT         REQUESTED_DATE,  COUNT(Orders) REQUESTED_ORDERS

FROM            SVCO

WHERE  (TRUNC(UCBSVCO_REQUESTED_DATE) BETWEEN  TRUNC(SYSDATE)AND TRUNC(SYSDATE+5))

GROUP BY REQUESTED_DATE

ORDER BY 1

I need to set a Flag to Y or N based on the following requirement  ;

if requested orders >=350 and <=399 or  >=400 set flag to Y; if already the flag is set to Y by previous run  then flag should be N

Below is the sample scenarios. This query will be run everyday

    First day run

Second day Run

Flag for 6/26/2016 is N because it already been set to Y for last run it will be N till the requested orders are crossing 400;then the flag would be Y.

6/27/2016 flag in Y ; because it was not in the previous run and it crossed 350

Third DayRun

6/25/2016 flag is Y  because it never crossed 350 in previous run and never set a flag ;

6/26/2016 flag is still N becasue it never crossed 400 Yet

same with 6/27/2016

Forth day Run

6/26/2016 is set to Y becasue it crossed 400.

6/27/2016 is still N becasue it didt cross 400

And so on .

Can anyone tell me how to implement this. I can use procedure or temp tables etc..

Thanks,

Ann