group by 子句中的 case 语句答案

【问题标题】：Case statement in group by clausegroup by 子句中的 case 语句
【发布时间】：2021-11-09 02:41:24
【问题描述】：

我当前的查询有效，但我似乎无法获得另一个列名来解释数据是什么。

查询：

SELECT 
    SUM(item_subtotal) AS rev
FROM 
    [ADAS].[dbo].[ADAS_ORDERS] x
LEFT JOIN 
    ADAS.dbo.ADAS_SUBSCRIPTIONS y ON x.SUBSCRIPTION_KEY = y.SUBSCRIPTION_KEY
                                  AND x.CUSTOMER_ID = y.customer_id
                                  AND x.ITEM_NUM = y.ITEM_NUM
WHERE
    x.ORDER_DATE BETWEEN '10-01-2021' AND '10-31-2021'
    AND x.ORDER_STATUS = 'success' 
    AND x.IMPULSE_FLG = 'n'
GROUP BY
    CASE 
        WHEN y.OFFER_ID IS NULL 
            THEN 'Null' 
        WHEN y.OFFER_ID IN ('1882', '1883', '4554', '4576') 
            THEN 'in-store' 
        ELSE 'web'  
    END
ORDER BY 
    1

结果

如何让另一列有名称？

【问题讨论】：

'Null' 不是 null，这是一个说空的文本。跳过这些引号并改用真正的NULL。（保留这些假空值只会遇到更多问题。）

标签： sql case ssms

【解决方案1】：

您也可以尝试在您的选择/投影中包含 group by 中的 case 表达式，例如

SELECT 
sum(item_subtotal)as rev,

  case when y.OFFER_ID is null then 'Null' 
  when y.OFFER_ID in('1882','1883','4554','4576') then 'in-store' else 'web' end as offer_location

  FROM [ADAS].[dbo].[ADAS_ORDERS] x
  left join ADAS.dbo.ADAS_SUBSCRIPTIONS y on x.SUBSCRIPTION_KEY = y.SUBSCRIPTION_KEY
  and x.CUSTOMER_ID = y.customer_id
  and x.ITEM_NUM = y.ITEM_NUM
  where x.ORDER_DATE between '10-01-2021' and '10-31-2021'
  and x.ORDER_STATUS = 'success' 
  and x.IMPULSE_FLG = 'n'
  group by  case when y.OFFER_ID is null then 'Null' 
  when y.OFFER_ID in('1882','1883','4554','4576') then 'in-store' else 'web' end
  order by 1

【讨论】：