Schedules are named, reusable calendar objects. They may be used for multiple jobs. Instead of declaring the same schedule for different jobs, just define it once and use it as a named schedule for different job definitions.

The schedule is created using DBMS_SCHEDULER.CREATE_SCHEDULE

PROCEDURE CREATE_SCHEDULE(
SCHEDULE_NAME
START_DATE
REPEAT_INTERVAL
END_DATE
COMMENTS
)

In this example a new schedule is created, it is defined to run hourly at an interval of six hours. This schedule is defined to start at invocation time and runs indefinitely.

BEGIN
DBMS_SCHEDULER.CREATE_SCHEDULE(
schedule_name => 'demo_schedule',
start_date => SYSTIMESTAMP,
end_date => null,
repeat_interval => 'FREQ=HOURLY;INTERVAL=6',
comments => 'Hourly schedule at an interval of six hours');
END;