Improve company productivity with a Business Account.Sign Up

x
?
Solved

Unable to truncate a table referenced by other tables using foreign keys

Posted on 2001-06-25
3
Medium Priority
?
1,653 Views
Last Modified: 2008-03-10
Table A has userid as a primary key, table B has userid as a primary key and references A.userid thru a foreign key, even if both tables are empty, I cannot truncate table A, why ?
I can delete table A by setting 'on delete cascade' option in the foreign key constraint, is
there a similar option for truncate ?
0
Comment
Question by:AtulPadhye
3 Comments
 
LVL 36

Accepted Solution

by:
Mark Geerlings earned 150 total points
ID: 6225345
Why can you not truncate a parent table?  Here is the quote from the Oracle8.1.6 documentation:

"You cannot truncate the parent table of an enabled referential integrity constraint. You must disable the constraint before truncating the table. (An exception is that you may truncate the table if the integrity constraint is self-referential.)"

No, I don't know of a way around this.  In fact, just disabling the foreign key constraint is not always enough.  I usually need to drop the foreign key constraint(s) first, then truncate the table and re-create the constraint(s), if they need to be in place.

0
 

Expert Comment

by:bbchang97
ID: 6225351
It won't allow u to delete the master records if child exists.  Since, without the master record, it's a violation for the forigen key constraints.

By using cascade delete, it's basically remove all child records related to the master row.

Ususally, if I'm trying to clean up both master and detail tables by using 'TRUNCATE' statement, I'll disable the foreign key ('ALTER TABLE XXX disable contraints FK_XXX'). I could then truncate both tables.  Afterwards, I could enable the foreign key again.

Hope this helps.
0
 
LVL 1

Expert Comment

by:ashokskumar
ID: 6225358
Hi,

As Delete handles row by row, it does with cascade option.
Truncate option handles on entire table. You should disable the foreign key constraint and try truncate.

Ashok.
0

Featured Post

Free Tool: Path Explorer

An intuitive utility to help find the CSS path to UI elements on a webpage. These paths are used frequently in a variety of front-end development and QA automation tasks.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Note: this article covers simple compression. Oracle introduced in version 11g release 2 a new feature called Advanced Compression which is not covered here. General principle of Oracle compression Oracle compression is a way of reducing the d…
From implementing a password expiration date, to datatype conversions and file export options, these are some useful settings I've found in Jasper Server.
This video shows how to set up a shell script to accept a positional parameter when called, pass that to a SQL script, accept the output from the statement back and then manipulate it in the Shell.
This video shows how to configure and send email from and Oracle database using both UTL_SMTP and UTL_MAIL, as well as comparing UTL_SMTP to a manual SMTP conversation with a mail server.

588 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