Re: Primary key

Any foreign key constraint referencing the primary key of table A would have to be changed as well, which means dropping these particular constraint(s) or adding fieldz to the referencing table(s) and foreign key constraint(s).

Gert-Jan

Lim Chin Yee wrote:

> Table A's primary key is made up of 2 fields( fieldx and fieldy)
> If i were to add in a new field(fieldz) and make it a primary key as
> well,
> what are the consequences?
>
> consequences that i've thought of.
> 1. since fieldz is of null value, existing data cannot be validated
> since the constraints cannot work.
>
> p.s: all 3 fields shld be NON-NULL
>
> TIA

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