Hi

I have 2 tables:

CREATE TABLE users (
id_user INTEGER NOT NULL GENERATED
ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
name VARCHAR(30),
PRIMARY KEY (id_user)
);

CREATE TABLE articles (
id_article INTEGER NOT NULL GENERATED
ALWAYS AS IDENTITY (START WITH 1, INCREMENT BY 1),
creator SMALLINT NOT NULL,
PRIMARY KEY (id_article)
FOREIGN KEY (creator) REFERENCES users (id_user)
);

Second table doesn`t create.
Error message is:

ERROR X0Y44: Constraint 'SQL061110025111171' is invalid: there is no unique or primary key constraint on table 'APP.UZIVATELE' that matches the number and types of the columns in the foreign key.

Where is the problem?

The reason is:
id_user is INTEGER
creator is SMALLINT
and INTEGER nad SMALLINT are non-full-compatible types.

If creator is INTEGER, all is OK.