How to get previous days execution time?

Question

Hello All,
I have below 3 tables in my Oracle Database --
1) Table jobs
Job ID  Job Name
1      ABC
2      PQR
3      XYZ
2) Table Job_Tasks
Task_ID   TASK_NAME  Job_ID 
  T1              T_ABC            1
  T2              T_ABE            1
  T3             T_ABD            1
  T4             T_PQS            2
  T5             T_PQT            2
  T6             T_PQU            2
  T7             T_XYA            3
  T8             T_XYZZ           3
  T9             T_XYYA           3
3) Job_LOG_Table
JOB_SEQ  JOB_ID  JOB_NAME   START_TIME  END_TIME           STATUS
1111              1        ABC    06/09/2013 11:00     06/09/2013 13:00   COMPL
1234              1        ABC    07/09/2013 11:30     07/09/2013 13:30   COMPL
1235              1        ABC    08/09/2013 11:30     08/09/2013 13:30   COMPL
1244              1        ABC    09/09/2013 11:00     09/09/2013 13:00   COMPL
1354              1        ABC    10/09/2013 11:30      10/09/2013 13:30   RUNNING
Question Is --
   I would like to display the job status from yesterday and from time 20:00 onwards.. ie. it should display the job_SEQ 1354. ( start_time >= (sysdate-1)||'20:00:00') and  also want to disaply previous days execution time for same job (ie. for 9th Sep).
The result should be --   Job_name PREV_START_TIME, PREV_END_TIME, TODAYS_START_TIME, TODAYS_END_TIME, STATUS
  As I am displaying the jobs from yesterday 20:00 hour onwards.. I am unable to get previous execution time for the same job.
I tried with Analylitical function LAG  but it's showing PREV_START_TIME.and PREV_END_TIME as BLANK.
Could you please help me to resolve the issue?
Thank you in advance.

Answer 1

As suggessted by Mike,  below is the modification I have done in my sql and I think it's working now....
I will check for more volume of data and confirm.  --
select original_sql as
select w.job_id,
w.job_name,
r.start_time,
r.end_time,
r.status
from
  jobs w,
  job_log_table r
where
  r.job_id=w.job_id
select job_id,job_name,
(select start_time from job_log_table j where j.job_id=os.job_id and j.start_time>=sysdate-2 and rownum <2) prev_start_time,
start_time,
end_time,
status
from Original_sql os
where
os.start_time>=to_date(to_char(sysdate-1,'DD/MM/YYYY') || ' 20:00:00','Dd/MM/YYYYHH24:MI:Ss')
as of now, I am getting the below result --
job_id,  job_name  prev_start_time,      prev_end_time,            curr_start_time,           curr_end_time,           status 
       1           ABC  09/09/2013 11:30   09/09/2013 13:00      10/09/2013 11:30          10/09/2013 13:30          RUNNING
Thank you !