Вы определили первичный ключ уровня столбца и уровня таблицы для той же таблицы. Вот почему вы получаете слишком много ошибок первичного ключа
Попробуйте это
CREATE TABLE staff
(
staff_id INTEGER NOT NULL,
staff_name VARCHAR (30) NOT NULL,
staff_surname VARCHAR (30) NOT NULL,
branch VARCHAR (10) NOT NULL,
jobrole VARCHAR (15) NOT NULL,
staff_contactno INTEGER NOT NULL,
CONSTRAINT pk_staff PRIMARY KEY (staff_id)
);
CREATE TABLE owner
(
owner_id INTEGER NOT NULL,
owner_name VARCHAR (30) NOT NULL,
owner_surname VARCHAR (30) NOT NULL,
owner_addressln1 VARCHAR (50) NOT NULL,
owner_addressln2 VARCHAR (50) NOT NULL,
owner_county VARCHAR (26) NOT NULL,
owner_postcode VARCHAR (7) NOT NULL,
owner_contactno INTEGER NOT NULL,
owner_email VARCHAR (50) NOT NULL UNIQUE,
CONSTRAINT pk_owner PRIMARY KEY (owner_id)
);
CREATE TABLE client
(
client_id INTEGER NOT NULL,
client_name VARCHAR (30) NOT NULL,
client_surname VARCHAR (30) NOT NULL,
client_contactno INTEGER NOT NULL,
client_email VARCHAR (50) NOT NULL,
CONSTRAINT pk_client PRIMARY KEY (client_id)
);
CREATE TABLE property
(
property_id INTEGER NOT NULL,
owner_id INTEGER NOT NULL,
property_addressln1 VARCHAR (50) NOT NULL,
property_addressln2 VARCHAR (50) NOT NULL,
property_county VARCHAR (26) NOT NULL,
property_postcode VARCHAR (7) NOT NULL,
property_type VARCHAR (15) NOT NULL,
property_bedrooms INTEGER NOT NULL,
availability VARCHAR (15) NOT NULL,
valuation INTEGER NOT NULL,
fk1_owner_id INTEGER NOT NULL,
fk2_staff_id INTEGER NOT NULL,
fk3_client_id INTEGER NOT NULL,
CONSTRAINT pk_property PRIMARY KEY (property_id, fk1_owner_id),
CONSTRAINT fk1_property_to_owner FOREIGN KEY(fk1_owner_id) REFERENCES owner(owner_id) ON DELETE restrict on update cascade,
CONSTRAINT fk2_property_to_staff FOREIGN KEY(fk2_staff_id) REFERENCES staff(staff_id) ON DELETE restrict on update cascade,
CONSTRAINT fk3_property_to_client FOREIGN KEY(fk3_client_id) REFERENCES client(client_id) ON DELETE restrict on update cascade
);
Примечание. Я не уверен в назначении столбцов owner_id и fk1_owner_id в таблице свойств. Кажется, дубликат столбца. Если он повторяется, удалите столбец owner_id из таблицы свойств