Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium


ER Modeling - Difference between Initially Deferred and Deferrable

Posted on 2005-03-07
Medium Priority
Last Modified: 2012-05-05
What's the difference between initially deferred and deferrable?  And, do these have anything to do with triggers?
Question by:lcor
  • 2
LVL 13

Accepted Solution

bochgoch earned 2000 total points
ID: 13476541
With an immediate constraint, if a user enters data that violates a constraint, the statement is rolled back and Oracle signals an error.

Deferred integrity constraints are those that are not enforced until the user attempts to commit the transaction. At the time of the commit, if any data entered during the transaction violates an integrity constraint, Oracle will then rollback the entire transaction and signal an error to the user.

Not all constraints in the database can be set to deferrable. Only when the constraint is created with the deferrable option can user processes set the constraint as deferrable. If the constraint is created with the not deferrable option (the default), then user processes will always be bound by immediate integrity constraint.

Along with defining whether a constraint is deferrable or not, you can also set its default behavior with the initially deferred and initially immediate statement. The initially deferred option will enable the constraint as deferrable by default whereas the initially immediate option requires the user process to explicitly set the transaction or session to deferrable.
LVL 13

Expert Comment

ID: 13476583
So there isn't a difference as such -- the initially deferred option will enable the constraint as deferrable by default....



Author Comment

ID: 13478621
Excellent and to the point!

Featured Post

Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Microsoft Jet database engine errors can crop up out of nowhere to disrupt the working of the Exchange server. Decoding why a particular error occurs goes a long way in determining the right solution for it.
Exchange database can often fail to mount thereby halting the work of all users connected to it. Finding out why database isn’t mounting is crucial and getting the server back online. Stellar Phoenix Mailbox Exchange Recovery is a champion product t…
In this video, Percona Solution Engineer Rick Golba discuss how (and why) you implement high availability in a database environment. To discuss how Percona Consulting can help with your design and architecture needs for your database and infrastr…
With just a little bit of  SQL and VBA, many doors open to cool things like synchronize a list box to display data relevant to other information on a form.  If you have never written code or looked at an SQL statement before, no problem! ...  give i…
Suggested Courses

564 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question