-- 分类表
CREATE TABLE categories
(
    id         INTEGER PRIMARY KEY GENERATED ALWAYS AS IDENTITY,
    name       TEXT        NOT NULL,
    code       TEXT UNIQUE NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    updated_at TIMESTAMPTZ
);

CREATE TRIGGER update_categories_updated_at
    BEFORE UPDATE
    ON categories
    FOR EACH ROW
EXECUTE FUNCTION update_updated_at_column();

COMMENT ON COLUMN categories.id IS '分类ID';
COMMENT ON COLUMN categories.name IS '分类名称';
COMMENT ON COLUMN categories.code IS '分类编码';