-- 显式执行一次；只创建阅读目标相关表，不修改已有业务表。
CREATE TABLE IF NOT EXISTS reading_goals (
    id VARCHAR(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
    name VARCHAR(60) NOT NULL,
    start_date DATE NOT NULL,
    end_date DATE NOT NULL,
    sources JSON NOT NULL COMMENT '加入目标时的书单名称，不追踪书单后续变更',
    created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (id)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci COMMENT='阅读目标';

CREATE TABLE IF NOT EXISTS reading_goal_books (
    goal_id VARCHAR(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
    book_id VARCHAR(64) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL,
    PRIMARY KEY (goal_id, book_id),
    CONSTRAINT fk_reading_goal_books_goal FOREIGN KEY (goal_id)
        REFERENCES reading_goals (id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
COMMENT='目标书籍成员；不关联书架表，避免移出书架时丢失目标成员';