Using decode function without negative values

Question

Hi friends
I am using oracle 11g
I have at doubt regarding the following.
create table Device(Did char(20),Dname char(20),Datetime char(40),Val char(20));
insert into Device values('1','ABC','06/13/2012 18:00','400');
insert into Device values('1','abc','06/13/2012 18:05','600');
insert into Device values('1','abc','06/13/2012 18:55','600');
insert into Device values('1','abc','06/13/2012 19:00','-32768');
insert into Device values('1','abc','06/13/2012 19:05','800');
insert into Device values('1','abc','06/13/2012 19:10','600');
insert into Device values('1','abc','06/13/2012 19:15','900');
insert into Device values('1','abc','06/13/2012 19:55','1100');
insert into Device values('1','abc','06/13/2012 20:00','-32768');
insert into Device values('1','abc','06/13/2012 20:05','-32768');
Like this I am inserting data into table for every 5 minutes Here i need the result like
output:
Dname 18:00 19:00 20:00
abc 400 -32768 -32768
to retrieve this result i am using decode function
SELECT Dname,
MAX(DECODE ( rn , 1,val )) h1,
MAX(DECODE ( rn , 2, val )) h2,
FROM
(SELECT Dname,Datetime,row_number() OVER
(partition by Dname order by datetime asc) rn FROM Device
where substr(datetime,15,2)='00' group by Dname.
According to above data expected result is
Dname 18:00 19:00 20:00
abc 400 600(or)800 1100
This means I dont want to display negative values instead of that values i want to show previous or next value.
Edited by: 913672 on Jul 2, 2012 3:44 AM

Answer 1

Are you looking for something like this?
select * from
select dname,
       datetime,
       val,
       lag(val) over (partition by upper(dname) order by datetime) prev_val,
       lead(val) over (partition by upper(dname) order by datetime) next_val,
       case when nvl(val,0)<0  and lag(val) over (partition by upper(dname) order by datetime) >0 then
         lag(val) over (partition by upper(dname) order by datetime)
       else 
         lead(val) over (partition by upper(dname) order by datetime)
       end gt0_val
from device
order by datetime
where substr(datetime,15,2)='00';Please take a look at the result_column gt0_val.
Edited by: hm on 02.07.2012 04:06