| |
 |
|
Oracle Tips by Burleson |
Chapter 3 - Time-Based Job Scheduling
Calendar Syntax in
Oracle10g
-
When there are not enough clauses to determine the precise
run date, the missing clauses are derived from the start_date.
For example, if there is no bysecond clause in the calendar
string, the value of seconds from the start_date is used to
create one.
-
When a number range is not fixed, the
last value of the range can be determined using a negative integer
as a count-back. As such bymonthday=-1 equates to the last
day of the month. The documentation states that count-backs are not
supported for fixed number ranges such as those used by the bymonth,
byhour, byminute and bysecond clauses, but they do appear to work
consistently.
-
The first day of the week is Monday.
-
A calendar string cannot specify time
zones. Instead the time zone is derived from one of the following
places in this order: the start_date, the current session’s
time zone, the DEFAULT_TIMEZONE scheduler attribute, or time zone
returned by the systimestamp function.
Now that calendar syntax has been introduced in
detail, the following section will compare the use of PL/SQL
expressions and the use of calendar syntax for scheduling jobs.
Complex Date Rules
for Job Execution
Prior to Oracle10g, the only way to define a
jobs repeat interval was to use a PL/SQL expression that evaluated
to a date. In Oracle10g, the calendar syntax is the preferred way
to define a jobs repeat interval, although PL/SQL expression can
still be used if they evaluate to a timestamp. In this section we
will compare how each method works.
|
Download your Oracle scripts now:
www.oracle-script.com
The
definitive Oracle Script collection for every Oracle professional DBA
|
|
