Calculate the SUM of multiple rows from one table and have it written to another table, weekly

Question

I am not an experienced SQL coder and sort of learn as I go. I have a task that needs to be executed automatically on a weekly basis. There's a few parts to this job:

1) Calculate the SUM of multiple rows from a couple of columns.

select SUM(TOTAL_COST) from TABLE_1 and select SUM(TOTAL_HOURS) from TABLE_1

2) Write the 2 SUMs from TABLE_1 to 2 columns in TABLE_2.

Let's call these columns: SUM_OF_COST and SUM_OF_HOURS from Table_2

3) This job needs to be executed weekly.

BEGIN
  DBMS_SCHEDULER.SET_ATTRIBUTE (
  name         =>  'update_job',
   attribute    =>  'repeat_interval',
   value        =>  'freq=weekly; byday=wed');
END;
/

The codes above are just from my understanding of I THINK what would be used. I know I have to write the entire job from the first 2 steps above into a package? I'm assuming I would reference that package in the job (step 3). I need help with how I would go about writing this. Does the SUMs need to be written to another column before they can be written to TABLE_2 or can it calculate the SUM and then write the value to TABLE_2 without storing that value in TABLE_1? How do I piece together the code to do the calculations and then write to the second table? Any help would be greatly, greatly, appreciated. Thank you!

Answer 1

You are in right way.

You need to create a procedure that will be performed every week.

CREATE OR REPLACE PROCEDURE sum_weekly IS
BEGIN
 INSERT INTO TABLE_2(SUM_OF_COST ,SUM_OF_HOURS ) (SELECT SUM(cost),SUM(hour) FROM TABLE_1)
 COMMIT;
END;

More about insert select syntax.

Then you need create schedule:

BEGIN
 DBMS_SCHEDULER.CREATE_JOB (
  job_name             => 'my.sum_weekly.schedule',
  job_type             => 'PLSQL_BLOCK',
  job_action           => 'BEGIN sum_weekly(); END;',
  start_date           =>  sysdate,
  repeat_interval      => 'FREQ=WEEKLY', 
  enabled              =>  TRUE,
  comments             => 'Gather table statistics from Table 1 to Table 2');
END;

Examples for repeat_interval.

FREQ=HOURLY;INTERVAL=4
every 4 hour
FREQ=HOURLY;INTERVAL=4;BYMINUTE=10;BYSECOND=30
every 4 hours, 10 minutes, 30 seconds of;
FREQ=YEARLY;BYYEARDAY=-276
every 31 th March;
FREQ=YEARLY;BYMONTH=MAR;BYMONTHDAY=31
every 31 th March;

To check correct set interval

DECLARE   next_run_date   TIMESTAMP;
BEGIN
 DBMS_SCHEDULER.EVALUATE_CALENDAR_STRING (
 'FREQ=HOURLY;INTERVAL=4;BYMINUTE=10;BYSECOND=30'
 ,SYSTIMESTAMP
 ,NULL
 ,next_run_date) ;
DBMS_OUTPUT.PUT_LINE ( 'next_run_date: ' || next_run_date );
END;

To see your schedules use following query:

SELECT job_name, state, enabled FROM user_scheduler_jobs;