Oracle sql: not able to add foreign key to table -> invalid identifier?

You are refereing to persid which is not a column in table species thus the error.

You are refereing to persid which is not a column in table species thus the error... EDIT - As per comments: It means that you need some column in species to be used as foreign key... if there is no such column then you need to build one in before you can create that constraint. Like this: alter table species add persid number(8) not null ; alter table species add constraint species_person_fk foreign key (persid) references person (persid) ; Depending on your data model, SPECIES. PERSID may be optional or mandatory.

– samjam Nov 14 '11 at 11:09 @samjam yes, it means that you need some column in species to be used as foreign key... if there is no such column then you need build one in before you can create that constraint. – Yahia Nov 14 '11 at 12:04 @samjam please don't forget to mark as accepted answers that are of help (see meta.stackoverflow.Com/questions/5234/…) – Yahia Nov 14 '11 at 12:05.

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