函数round（双精度，整数）不存在（行：4）

Question

我正在尝试在 datalemur 上编写查询，但我的解决方案没有被接受

给我抛出错误：

function round(double precision, integer) does not exist (LINE: 4)

问题：链接

我的询问未被接受：

SELECT
    EXTRACT(MONTH FROM submit_date) AS mth,
    product_id                      AS product,
    round((AVG(stars)),
          2)                        AS avg_stars
FROM
    reviews
GROUP BY
    EXTRACT(MONTH FROM submit_date),
    product_id
ORDER BY
    mth,
    product;

我犯了什么错误，你能帮我找出来吗？

Answer 1

你必须将整数转换为数字

  SELECT
        EXTRACT(MONTH FROM submit_date) AS mth,
        product_id                      AS product,
        round(AVG(stars) ::numeric,2)
                                    avg_stars
    FROM
        reviews
    GROUP BY
        EXTRACT(MONTH FROM submit_date),
        product_id
    ORDER BY
        mth,
        product;