由 Oracle SQL 生成 ERD 关系图

CREATE TABLE users (
    id NUMBER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    email       VARCHAR2(255) NOT NULL UNIQUE,
    full_name   VARCHAR2(120),
    is_active   NUMBER(1) NOT NULL,
    created_at  TIMESTAMP NOT NULL
);

CREATE TABLE orders (
    id NUMBER GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY,
    user_id     NUMBER NOT NULL REFERENCES users(id),
    total       NUMBER(12,2) NOT NULL,
    note        CLOB,
    placed_at   TIMESTAMP NOT NULL
);