I use Firebird (v. WI-T1.0.0.679).

I tried to add the following constraint to table ART:

ALTER TABLE ART ADD CONSTRAINT ART_INVALIDCOD_ACC FOREIGN KEY (COD_ACC)
REFERENCES TB_ACC (COD_ACC)

This is the error message I get:

"violation of foreign key constraint INTEG_73 on table tb_acc"

I am puzzled: INTEG_73 is the primary key of TB_ACC, defined as

Primary key (COD_ACC)

Accordingly, I have only distinct values of COD_ACC in TB_ACC.

I do have replicated values of COD_ACC in ART, but this should be natural.

Why is Firebird complaining ?

TIA

Duilio Foschi