Re: CTAS only recreate non-NULL contrainsts - WHY?
- From: Robert Freeman <robertgfreeman@xxxxxxxxx>
- To: htmldeveloper@xxxxxxxxx, Oracle-L Freelists <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 24 Mar 2008 22:40:33 -0700 (PDT)
Well, think about it.
If I do a CTAS which is a join between two tables, then which primary key gets
moved over? You can define the primary key in the CTAS command if you need to
like this:
create table newemp (empid primary key)
as select empid from emp;
With respect to FK's, the same logic applies.... you could be creating rows
that would violate the existing FK (say with an outer join).
RF
Robert G. Freeman
Author:
Oracle Database 11g New Features (Oracle Press)
Portable DBA: Oracle (Oracle Press)
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Oracle9i New Feature
Blog: http://robertgfreeman.blogspot.com (Oracle Press)
----- Original Message ----
From: Peter Teoh <htmldeveloper@xxxxxxxxx>
To: Oracle-L Freelists <oracle-l@xxxxxxxxxxxxx>
Sent: Monday, March 24, 2008 10:33:26 PM
Subject: CTAS only recreate non-NULL contrainsts - WHY?
It is known that CTAS only recreate the constraints if it is non-NULL,
while others like primary key, foreign keys are all not created.
Is there any reason why?
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