-- 制約を持つ表の作成例
CREATE TABLE orders (
order_id NUMBER PRIMARY KEY,
customer_id NUMBER NOT NULL,
order_date DATE DEFAULT SYSDATE,
amount NUMBER(10,2) CHECK (amount > 0),
status VARCHAR2(10) CHECK (status IN ('PENDING','SHIPPED','DONE')),
CONSTRAINT fk_customer FOREIGN KEY (customer_id) REFERENCES customers(customer_id)
);
-- 既存の表に制約を追加する
ALTER TABLE orders ADD CONSTRAINT uq_order_ref UNIQUE (order_ref);