Question

我有一个可以拥有多个专业位置的数据集。我正在尝试根据以下标准选择一种专业：

如果Primary ='Y'，则选择Primary over Boardcertified
如果Primary ='N'且Boardcertified ='Y'，则选择Boardcertified

如果两个='N'，则选择任一记录

declare @t table(id int, location varchar(250), specialty varchar(250), boardcertified char, primaryspeciality char)

insert into @t values(1, 'Dallas', 'Maternal', 'Y', 'N'),
                     (1, 'Dallas', 'Obstetrics', 'Y', 'Y'),
                     (2, 'Plano', 'Maternal', 'Y', 'N'),
                     (2, 'Plano', 'Peds', 'N', 'N'),
                     (3, 'Arlington', 'Peds', 'N', 'N'),
                     (3, 'Arlington', 'Maternal', 'Y', 'Y')

我一直试图通过窗口函数来解决这个问题，如下所示：

    select * from
    (
    select *, row_number()over(partition by id, location
                               order by case when primaryspeciality = 'Y' then 1
                                         when boardcertified = 'Y' then 2
                                         end desc) as rn
from @t)a
    where rn = 1

这给了我以下结果：

    id    location   specialty    boardcertified   primaryspecialty 
    1       Dallas     Maternal     Y                 N

我真正想要的是：

    id     location   specialty    boardcertified   primaryspecialty
    1       Dallas    Obstetrics      Y               Y

由于达拉斯和Obstretics的primaryspecialty ='Y'，我想要那个记录。我不确定我在这里做错了什么。

Answer 1

我认为这就是你所追求的：

WITH CTE AS(
    SELECT *,
           ROW_NUMBER() OVER (PARTITION BY id, [location]
                              ORDER BY CASE primaryspeciality WHEN 'Y' THEN 0 ELSE 1 END,
                                       CASE boardcertified WHEN 'Y' THEN 0 ELSE 1 END,
                                       id) AS RN
    --If you want the id to be random each time when they are both 'Y' (as you said it could be any), replace id with NEWID()
    FROM @t)
SELECT *
FROM CTE
WHERE RN = 1;

请注意多个CASE表达式的使用。

SQL窗口函数排序问题

1 个答案: