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Editorial Team
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Asked: 2026-06-15T12:08:32+00:00

I have a table called TBLAPPLICATION which holds data specifying an individual’s ID number

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I have a table called TBLAPPLICATION which holds data specifying an individual’s ID number and a JobID of the job they have applied for. Each ID number can have an unlimited number of applications, providing the JobID is different every time, thus having no duplicate applications.

create or replace
   TRIGGER trg_duplicateapplication BEFORE INSERT ON tblapplication FOR EACH ROW

BEGIN
   IF :NEW.studentrecordnumber_fk_nn = :OLD.studentrecordnumber_fk_nn THEN
      IF :NEW.jobid_fk_nn = :OLD.jobid_fk_nn
         THEN RAISE_APPLICATION_ERROR( -20003, 'Error: duplicate application. You have already applied for this position.');
      END IF;
   END IF;
END;

So the above code doesn’t work, and I wish it would. Could anyone please highlight my mistake? 🙂

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1 Answer

  1. Editorial Team

    As it stands, your trigger is comparing the inserted values (:NEW.studentrecordnumber_fk_nn etc) with a non-existent :OLD (:OLD has no meaning to an INSERT trigger—it’s fields are always null).

    That aside, this should almost certainly be accomplished by DRI instead of a trigger at all— how about a unique index on (studentrecordnumber_fk_nn, jobid_fk_nn)?

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