relationship between tables hsqldb

Question

I need to create two tables in relationship one to many. I have created following statements. Maven gives me an error about "unique constraint". I don't know how to fix it, someone can explain me how to create correct relationship in this example?

CREATE TABLE Owner(
owner_id INT GENERATED BY DEFAULT AS IDENTITY, 
firstname varchar(20), 
lastname varchar(20)
)
"CREATE TABLE Picture(
picture_id INT GENERATED BY DEFAULT AS IDENTITY, 
owner_id INT, name varchar(20), 
width INT, height INT, 
FOREIGN KEY(pic_owner_id) REFERENCES Owner(owner_id)
)

Answer 1

You need to add a primary key.

CREATE TABLE Owner( owner_id INT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY, firstname varchar(20), lastname varchar(20) )