Question

对于措辞不好的问题感到抱歉，但我正在使用以下查询整合客户记录：

select
 customer_key
,FIRST_VALUE(name          IGNORE NULLS) OVER(PARTITION BY customer_key ORDER BY last_updated_date desc ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS NAME
,FIRST_VALUE(county        IGNORE NULLS) OVER(PARTITION BY customer_key ORDER BY last_updated_date desc ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS COUNTRY
,FIRST_VALUE(country_code  IGNORE NULLS) OVER(PARTITION BY customer_key ORDER BY last_updated_date desc ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) AS COUNTRY_CODE
from            customers  cust

这将使用customer_key选择客户的最新记录。但对于国家/地区，我需要国家/地区代码与国家/地区在同一行，使用国家/地区字段作为驱动程序，但country_code列是NOT NULL字段。

例如，这个原始数据：

customer  Country  Country_Code Date
Dave      NULL     0            30/08/2017
David     UK       1            29/08/2017

需要显示为：

customer  Country  Country_Code
Dave      UK       1 
Dave      UK       1

但是使用我正在使用的选择查询，我得到了这个：

customer  Country  Country_Code
Dave      UK       0 
Dave      UK       0

有什么建议吗？

Answer 1

以下查询应该有效。

  SELECT FIRST_VALUE(NAME IGNORE NULLS) OVER (
        PARTITION BY customer_key ORDER BY last_updated_date DESC ROWS BETWEEN UNBOUNDED PRECEDING
                AND UNBOUNDED FOLLOWING
        ) AS NAME
    ,FIRST_VALUE(county IGNORE NULLS) OVER (
        PARTITION BY customer_key ORDER BY last_updated_date DESC ROWS BETWEEN UNBOUNDED PRECEDING
                AND UNBOUNDED FOLLOWING
        ) AS COUNTRY
    ,FIRST_VALUE((
            CASE 
                WHEN county IS NULL
                    THEN NULL
                ELSE country_code
                END
            ) IGNORE NULLS) OVER (
        PARTITION BY customer_key ORDER BY last_updated_date DESC ROWS BETWEEN UNBOUNDED PRECEDING
                AND UNBOUNDED FOLLOWING
        ) AS COUNTRY_CODE
FROM customers cust;

根据同一选择查询中的另一个值选择合并值？

1 个答案: