Re: referential intergrity

On 05-Mär-98 11:16:48 Tong Zhai wrote:

>Hi, all:
> we are setting up a db, one of the table is works_on, and the primary key
>for that table are composite of project_number and Employee_ssn, so by
>definition they can't be null, but if I do want to insert a record with
>null project_number, how can I do that ?

Hello,
you'll have to drop the primary key, alter the table to allow nulls for the project number and then create a unique index on project_number and employee_ssn.

>tong.

Hope that helps,
Lothar

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