从 SQL 中的特定月份提取条目

Question

我正在尝试从名为orders的表中计算 3 月份每个客户购买的总收入，其中order_date的格式为datetime时间（例如 2019-03-04）。 但是，我无法通过以下任一选项获得结果：

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;

还

WHERE EXTRACT(month from order_date) = '03'

或者

WHERE MONTH(order_date) = 03

也不行。 我的语法有什么问题？

Answer 1

感谢大家的投入，终于找到了正确的方法：

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;

有了这个，它将日期转换为时间戳并根据需要提取三月。

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

您是否考虑将 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，如果您让我们知道您获得了什么（如果有的话）结果，将会很有帮助。 您是收到错误消息还是只是没有返回预期值/行数？