Latest two max

Question

Hi
I have query
select * from
(select Server,CPU_TOT_UTIL,RUNDATETIME,dense_rank() over (partition by Server order by RUNDATETIME desc) rnk from utlz_tab
where RUNDATETIME > sysdate-1)
where rnk <3
Which gives following result set
SERVER     CPU_TOT_UTIL     RUNDATETIME     RNK
A     64     02/15/2010 06:58:52     1
A     77     02/15/2010 06:43:51     2
B     78     02/15/2010 07:01:01     1
B     94     02/15/2010 06:46:01     2
C     32     02/15/2010 06:58:52     1
C     33     02/15/2010 06:43:51     2
D     23     02/15/2010 06:58:52     1
D     52     02/15/2010 06:43:51     2
E     93     02/15/2010 06:56:51     1
E     100     02/15/2010 06:41:51     2
F     68     02/15/2010 07:00:21     1
F     27     02/15/2010 06:45:19     2
G     14     02/15/2010 07:01:19     1
G     66     02/15/2010 06:46:19     2
H     19     02/15/2010 07:00:53     1
H     24     02/15/2010 06:45:53     2
Objective: finding cpu usage for last two timestamp may be interval of (15 mins).
Output required here is when a server having cpu usage >90 for its last two timestamps.
Result would be for my example
SERVER     CPU_TOT_UTIL     RUNDATETIME     RNK
E     93     02/15/2010 06:56:51     1
E     100     02/15/2010 06:41:51     2
Please help me to get this result.
Thanks
Ranga

Answer 1

You can use lag and lead functions:
select * from
(select Server,CPU_TOT_UTIL,RUNDATETIME,dense_rank() over (partition by Server order by RUNDATETIME desc) rnk,
lag(CPU_TOT_UTIL) over (partition by Server order by RUNDATETIME desc) prev_cpu,
lead(CPU_TOT_UTIL) over (partition by Server order by RUNDATETIME desc) next_cpu
from utlz_tab
where RUNDATETIME > sysdate-1)
where rnk <3
and CPU_TOT_UTIL>90
and (prev_cpu>90 or next_cpu>90)Max
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