Re: Preferred method in creating primary key

On Thu, 14 Aug 2003 16:22:46 -0700, Daniel Morgan <damorgan_at_exxesolutions.com> wrote:
>Deferred constraints can not be violated. The only thing that happens when a constraint
>is deferred is that the validity checking waits until the commit.
>
>This can be of great value in loading tables where referential constraints exist and
>where it is time consuming or difficult to track down all of the various relationships
>between parents and children. You can insert all of the records in any order and then
>commit them.
>
>Deferring a primary key or unique constraint is quite a different matter. If it can't
>handle to constraint upon initial insertion ... it never will.

In a data warehousing-type situation, I have loaded data with a null primary key and then filled in the entire column with a single UPDATE statement referencing a sequence. It was much later that I found SQL*Loader could do fill in the values automatically using the SEQUENCE keyword, so the column would never be null.

John

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