從 SQL 中的特定月份提取條目

Question

我正在嘗試從名為orders的表中計算 3 月份每個客戶購買的總收入，其中order_date的格式為datetime時間（例如 2019-03-04）。 但是，我無法通過以下任一選項獲得結果：

WITH cte_orders AS
(
    SELECT
        cust_id,
        SUM(order_quantity * order_cost) AS revenue
    FROM
        orders
    WHERE 
        DATEPART('month', order_date) = 3
    GROUP BY 
        cust_id
)
SELECT cust_id, revenue 
FROM cte_orders;

還

WHERE EXTRACT(month from order_date) = '03'

或者

WHERE MONTH(order_date) = 03

也不行。 我的語法有什么問題？

Answer 1

感謝大家的投入，終於找到了正確的方法：

WITH cte_orders AS
(
    SELECT 
        cust_id,
        SUM(order_quantity * order_cost) AS revenue,
    FROM 
        orders
    WHERE
        EXTRACT('MONTH' FROM order_date :: TIMESTAMP) = 3
    GROUP BY
        cust_id
)

SELECT cust_id, revenue 
FROM cte_orders;

有了這個，它將日期轉換為時間戳並根據需要提取三月。

Answer 2

date_part呢？

WITH cte_orders AS
(select cust_id
    , SUM(order_quantity * order_cost) as revenue
from orders
WHERE date_part('month',TIMESTAMP order_date) = 3
group by cust_id)

select cust_id, revenue from cte_orders;

Answer 3

您是否考慮將 WHERE 子句放在 CTE 之外？

WITH cte_orders AS
(
    SELECT
        cust_id,
        SUM(order_quantity * order_cost) AS revenue
    FROM
        orders
    WHERE 
        DATEPART('month', order_date) = 3
    GROUP BY 
        cust_id
)
SELECT cust_id, revenue 
FROM cte_orders
WHERE MONTH(order_date) = 03;

此外，如果您讓我們知道您獲得了什么（如果有的話）結果，將會很有幫助。 您是收到錯誤消息還是只是沒有返回預期值/行數？