Questão de Banco de Dados — PostgreSQL — UFMT 2024
Banco de DadosPostgreSQL
- Código
- qg368159
- Banca
- UFMT
- Órgão
- UFMT
- Ano
- 2024
- Nível
- Superior
- Cargo
- Analista de Tecnologia da Informação
São dadas a seguir duas tabelas no banco de dados PostgreSQL: orders e customers.CREATE TABLE customers (customer_id SERIAL PRIMARY KEY,customer_name VARCHAR(100));CREATE TABLE orders (order_id SERIAL PRIMARY KEY,order_date DATE,customer_id INT,FOREIGN KEY (customer_id) REFERENCES customers(customer_id));Qual alternativa altera a definição dessa chave estrangeira de modo que, quando um registro na tabela customers for deletado, a coluna customer_id na tabela orders seja atualizada para NULL?
- AALTER TABLE ordersDROP CONSTRAINT orders_customer_id_fkey,ADD CONSTRAINT orders_customer_id_fkey FOREIGN KEY (customer_id)REFERENCES customers(customer_id) ON DELETE RESTRICT NULL;
- BALTER TABLE ordersDROP CONSTRAINT orders_customer_id_fkey,ADD CONSTRAINT orders_customer_id_fkey FOREIGN KEY (customer_id)REFERENCES customers(customer_id) ON DELETE CASCADE NULL;
- CALTER TABLE ordersDROP CONSTRAINT orders_customer_id_fkey,ADD CONSTRAINT orders_customer_id_fkey FOREIGN KEY (customer_id)REFERENCES customers(customer_id) ON DELETE SET DEFAULT NULL;
- DALTER TABLE ordersDROP CONSTRAINT orders_customer_id_fkey,ADD CONSTRAINT orders_customer_id_fkey FOREIGN KEY (customer_id)REFERENCES customers(customer_id) ON DELETE SET NULL;