尝试将多个键 ID 组合成单行，但列中的值不同

Question

TSQL - SQL 服务器

我正在根据非常具体的要求构建报告。我正在尝试将多个键 ID 组合成单行，但某些列中的值不同，因此 GROUP BY 不起作用。

SELECT count(tt.Person_ID) as CandCount, tt.Person_ID, 
CASE e.EthnicSuperCategoryID WHEN CandCount > 1 THEN 10 ELSE e.EthnicSuperCategoryID END as EthnicSuperCategoryID,
CASE e.Ethnicity_Id WHEN 1 THEN 1 ELSE 0 END as Black ,
CASE e.Ethnicity_Id WHEN 2 THEN 1 ELSE 0 END as White ,
CASE e.Ethnicity_Id WHEN 3 THEN 1 ELSE 0 END as Asian,
etc
FROM T_1 TT
JOINS
WHERE
GROUP

消息 102，级别 15，状态 1，第 4 行 '>' 附近的语法不正确。

这是结果（没有第一个 CASE）。注意人 3 陈述了多个种族。

SELECT count(tt.Person_ID) as CandCount, tt.Person_ID, 
CASE e.Ethnicity_Id WHEN 1 THEN 1 ELSE 0 END as Black ,
CASE e.Ethnicity_Id WHEN 2 THEN 1 ELSE 0 END as White ,
CASE e.Ethnicity_Id WHEN 3 THEN 1 ELSE 0 END as Asian,
etc
FROM T_1 TT
JOINS
WHERE
GROUP

这是意料之中的，但目标是将多个种族分配给 Ethnicity_Id 为 10（多个）。我还希望它们在一行中分组。

所以最终的结果应该是这样的：

所以我的问题有两个方面。如果候选人有超过 2 个种族，则将记录分配给 Ethnicity_Id 为 10。我还需要将重复的人员 ID 分组到一行中，同时显示列的所有结果。

Answer 1

这应该会带来你想要的结果：

SELECT Person_ID
     , ISNULL(ID_Dummy,Ethnicity_ID) Ethnicity_ID
     , MAX(Black) Black
     , MAX(White) White
     , MAX(Asian) Asian
  FROM @T T
 OUTER APPLY(SELECT MAX(10) FROM @T T2 
               WHERE T2.Person_ID = T.Person_ID 
                 AND T2.Ethnicity_ID <> T.Ethnicity_ID
            )EthnicityOverride(ID_Dummy)
 GROUP BY Person_ID, ISNULL(ID_Dummy,Ethnicity_ID)

Answer 2

您需要条件聚合。您的查询不完整，但想法是：

select 
    person_id, 
    sum(case ethnicity_id = 1 then 1 else 0 end) as black,
    sum(case ethnicity_id = 2 then 1 else 0 end) as white,
    sum(case ethnicity_id = 3 then 1 else 0 end) as asian
from ...
where ...
group by person_id

您可能需要max() 而不是sum()。此外，我没有得到所需结果中第二列的逻辑 - 也许这只是count(*)。

Answer 3

这将是我的方法

SELECT 
    person_id,
    CASE WHEN flag = 1 THEN Ethnicity_Id ELSE 10 END AS Ethnicity_Id,
    [1] as black,
    [2] as white,
    [3] as asian
FROM  
(
    SELECT 
        person_id, 
        Ethnicity_Id as columns,
        1 as n,
        MAX(Ethnicity_Id) over(PARTITION BY person_id) as Ethnicity_Id,
        COUNT(Ethnicity_Id) over(PARTITION BY person_id) as flag
    FROM 
        #example
) AS SourceTable  
PIVOT  
(  
    MAX(n) FOR columns IN ([1], [2], [3])  
) AS PivotTable;

• 使用常量将 Ethnicity_Id 列转换为多个列 1 让它抱怨你的预期结果。
• 使用 Max(Ethnicity_Id) 和 Partition By 来获取原始 Ethnicity_Id
• 使用 Count(Ethnicity_Id) 标记是否需要替换 Ethnicity_Id
  公元前 10 年，该 person_id 的行数超过 1 行

如果您需要添加更多种族，请在 ... IN ([1], [2], [3]) ... 和选择中添加 id