Generating dates from dbms_scheduler

The dbms_scheduler package allows you to create jobs that run at scheduled time periods, and you can get quite sophisticated in job scheduling dates.  See these examples of complex job scheduling with dbms_scheduler.

Also see these examples of complex date range using sysdate and interval, and see Dr. Tim Hall's book "Oracle Job Scheduling" for complete details on advanced job scheduling with dbms_scheduler.

An experienced DBA knows the internals of the Oracle packages and this knowledge allows them to develop novel uses for existing tools.  The mark of a real Oracle guru is being able to use tools in ways that they were not designed, like deploying multiple blocksizes for high performance in very large OLTP databases.

For another creative example, we see where David Aldridge has this outstanding article on using the dbms_scheduler evaluate_calendar_string procedure to generate a list of dates from Oracle.

This is a very creative and novel use of the dbms_scheduler package because dbms_scheduler was not originally designed to generate date lists. 

Using his list_of_dates function, you can create complex data generations including lists of holidays:

-- List of weekdays excluding public holidays

select *
from   table(
list_of_dates(
'WEEKDAYS;EXCLUDE=PUBLIC_HOLIDAYS',
sysdate    ,
null));

-- List of weekend and public holiday dates

select *
from   table(
list_of_dates(
'WEEKENDS,PUBLIC_HOLIDAYS',
sysdate    ,
null));

Give me a list of days for this year"

select *
from
 table(
   list_of_dates(
     'FREQ=DAILY;BYHOUR=0;BYMINUTE=0;BYSECOND=0',
      trunc(sysdate,'yyyy'),
      add_months(trunc(sysdate,'yyyy'),12)-1));

"Give me a list of the last-but-one day for each month from now to the end of the year"

select *
from
 table(
   list_of_dates(
     'FREQ=MONTHLY; BYMONTHDAY=-2;BYHOUR=0;BYMINUTE=0;BYSECOND=0',
     sysdate,
     add_months(trunc(sysdate,'yyyy'),12)-1));

"1am, 3am, 7am at 1pm every day from tomorrow for a very long time"

select *
from
  table(
    list_of_dates(
     'FREQ=DAILY; BYHOUR=1,4,7,13;BYMINUTE=0;BYSECOND=0',
     trunc(sysdate),
     date '9999-12-31'));

"First day of each calendar quarter etc"

select *
from
  table(
    list_of_dates(
     'FREQ=YEARLY;BYDATE=0101,0401,0701,1001;BYHOUR=0;BYMINUTE=0;BYSECOND=0',
     trunc(sysdate),
     date '9999-12-31'));

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