Re: Foreign Keys

From: ddf <oratune_at_msn.com>
Date: Tue, 25 Nov 2014 11:02:39 -0800 (PST)
Message-ID: <85f59206-99ba-492e-81c1-2227a7709070_at_googlegroups.com>

On Monday, November 24, 2014 9:25:56 AM UTC-7, ruben safir wrote:
> I have this very simple practice database is 11g and I can't add a foreign
> key to a table. Maybe someone can tell me what I'm doing wrong.
>
> I have table one
>
> create table employee(
> fname varchar2(20) NOT NULL, minit char(1),
> lname varchar2(20) NOT NULL, ssn number(9) NOT NULL,
> bdate date NOT NULL,
> address varchar2(50) NOT NULL,
> sex char(1) NOT NULL,
> salary float(12) NOT NULL, superssn number(9),
> dno number(2)
> );
>
> I set a primary key
>
> alter table employee add constraint pk_employee primary key (ssn)
> /
>
> I create table two
>
>
> create table works_on(
> essn number(9),
> pno number(2), hours float(5) );
>
>
> ALTER TABLE WORKS_ON ADD CONSTRAINT workson_essn FOREIGN KEY (ESSN)
> REFERENCES EMPLOYEE (SSN);
>
> SQL> _at_fk_workson_essn.sql ADD CONSTRAINT workson_essn
> *
> ERROR at line 2:
> ORA-02298: cannot validate (RUBEN.WORKSON_ESSN) - parent keys not found
>
> what is the error?
>
> --
> The Coin Hangout: http://www.coinhangout.com/home

It appears you have data in your child table and none in the parent. No parent record, no foreign key constraint.

David Fitzjarrell Received on Tue Nov 25 2014 - 20:02:39 CET