Help with nested select query

Question

Here is my code , i dont have any experience with writing the nested sql , i got the below code , which needs to be modified adding a case statement which will show util_rate for 2 conditions
1. given in where condition ( to_char(time_stamp,'HH24') >= '09' and to_char(time_stamp,'HH24') <= '19')
2.Apposite to the condition above (to_char(time_stamp,'HH24') < '09'and to_char(time_stamp,'HH24') > '19')
could anybody please help me in adding the 2nd condition to the below query , please share any documentation you have for learning how to write nested sql,
Thank you
select device,time_stamp,
sum(ActiveHRS)/sum(AvailHRS) as RATE
from
select device,time_stamp,
case when usage >0 then 1
else 0 end as ActiveHRS,
'1' as AvailHRS
from
select device,time_stamp,
sum(case
when state = 9 then 0
when state = 0 then 0
else 1 end) as usage
from A
where to_char(time_stamp,'HH24') >= '09'
and to_char(time_stamp,'HH24') <= '19'
and to_char(time_stamp, 'D') in (2,3,4,5,6)
group by device, time_stamp
group by device,time_stamp

Answer 1

Here is the DDL :
desc rumi_all
Name     Null   Type    
RUMI_DEVICE      VARCHAR2(20)
STATE         NUMBER(38) 
TIME_STAMP      DATE     
LOCATION       VARCHAR2(50) Here is some sample data :
RUMI_DEVICE   STATE   TIME_STAMP    LOCATION
10.45.28.86     0     15-JUN-10      WA-102
10.45.28.51     0     15-JUN-10      WA-102
10.45.28.63     0     15-JUN-10      WA-102
10.45.29.47     9     15-JUN-10      WA-120I used the below query to get the util for the hours 9am - 7pm
select rumi_device,time_stamp,
sum(ActiveHRS)/sum(AvailHRS) as RATE
from
select rumi_device,time_stamp,
case when usage >0 then 1
else 0 end as ActiveHRS,
'1' as AvailHRS
from
select rumi_device,time_stamp,
sum(case
when state = 9 then 0
when state = 0 then 0
else 1 end) as usage
from rumi_all
where to_char(time_stamp,'HH24') >= '09'
and to_char(time_stamp,'HH24') <= '19'
and to_char(time_stamp, 'D') in (2,3,4,5,6)
group by rumi_device, time_stamp
group by rumi_device,time_stamp
Acquired Out for the above query :
RUMI_DEVICE      TIME_STAMP     UTIL_RATE
10.45.29.47     15-JUN-10       0.234
10.45.28.63     15-JUN-10             0.123
10.45.29.47     15-JUN-10             0.987
10.45.29.47     16-JUN-10             0.23Desired output :I want 2 extra columns which shows util rate for the above condition i.e 9am - 7pm(core hours) and also opposite to that condition after 7pm - before 9am(say, non core hours)
Desired out put :
RUMI_DEVICE TIME_STAMP  Core_Util_Rate   Non_Core_UtilRate
10.45.29.4    15-JUN-10       0.234              0.003
10.45.28.63   15-JUN-10     0.123              0.001
10.45.29.47   15-JUN-10              0.987              0.023
10.45.29.47   16-JUN-10              0.23                  0Hope this helps in answering my question , and also could you please share some document to learn writing nested sql's , i always had tough time in understanding this :-(