根据值将 SQL 列拆分为多列

Question

我有一个 table 如下所示

Opp_ID     Role_Name     Role_User_Name
---------------------------------------
1          Lead          Person_one
1          Developer     Person_two
1          Developer     Person_three
1          Owner         Person_four
1          Developer     Person_five

我现在需要根据值将 Role_Name 列拆分为 3 个不同的列。我需要确保没有 NULL 值，所以 table 应该像下面的

Opp_ID     Lead        Developer     Owner
--------------------------------------------------
1          Person_one  Person_two    Person_four
1          Person_one  Person_three  Person_four
1          Person_one  Person_five   Person_four

我的代码目前是：

SELECT
    ID,
    CASE WHEN Role_Name = 'Lead' THEN Role_User_Name ELSE NULL END AS Lead,
    CASE WHEN Role_Name = 'Developer' THEN Role_User_Name ELSE NULL END AS Developer,
    CASE WHEN Role_Name = 'Owner' THEN Role_User_Name ELSE NULL END AS Owner
FROM 
    [table1]
WHERE 
    Role_Name IN ('Lead','Developer','Owner')

不幸的是 returns 这些结果：

Opp_ID     Lead        Developer     Owner
-------------------------------------------
1          Person_one  NULL          NULL
1          NULL        Person_two    NULL
1          NULL        Person_three  NULL
1          NULL        NULL          Person_four
1          NULL        Person_five   NULL

我假设要使它正常工作，您需要重新加入代码本身，但我似乎无法让它正常工作。

Answer 1

您可以切换到聚合：

SELECT ID,
       MAX(CASE WHEN Role_Name = 'Lead' THEN Role_User_Name END) AS Lead,
       MAX(CASE WHEN Role_Name = 'Developer' THEN Role_User_Name END) AS Developer,
       MAX(CASE WHEN Role_Name = 'Owner' THEN Role_User_Name END) AS Owner
FROM [table1]
WHERE  Role_Name IN ('Lead', 'Developer', 'Owner')
GROUP BY ID;

如果你可以有多个人，你可能想使用 STRING_AGG()。

请注意，我删除了 ELSE NULL。这是多余的。没有 ELSE 子句，CASE 表达式 returns NULL 当没有匹配时。

Answer 2

您还可以使用 first_value function on Pivot 结果如下

See working demo

select 
    opp_id,
    lead=COALESCE([lead],FIRST_VALUE([Lead]) over( order by opp_id )),
    Developer=COALESCE([Developer],FIRST_VALUE([Developer]) over( order by opp_id )),
    Owner=COALESCE([Owner],FIRST_VALUE([Owner]) over( order by opp_id ))
from 
(select opp_id,Role_Name,
 Role_User_Name,
 rn=row_number() over( partition by Role_Name order by (select 1))
 from
 table1)
 src
pivot
(max(Role_user_name) for role_name in ([Lead],[Developer],[Owner]))p

Answer 3

要应用每个开发人员并带领您的所有者进行 Opp_ID，您需要类似的内容：

SELECT o.opp_id
    , o.Role_User_Name AS Owner
    , l.Role_User_Name AS Lead
    , d.Role_User_Name AS Developer
FROM t1 AS o
LEFT OUTER JOIN t1 l ON o.opp_id = l.opp_id AND l.Role_Name = 'Lead'
LEFT OUTER JOIN t1 d ON o.opp_id = d.opp_id AND d.Role_Name = 'Developer'
WHERE o.Role_Name = 'Owner'

https://dbfiddle.uk/?rdbms=sqlserver_2017&fiddle=da4daea062534245bed474f93ffafbb7

Answer 4

我更喜欢使用交叉连接

select o.opp_id,
   o.role_user_name o, 
   l.role_user_name l, 
   d.role_user_name d
from t1 o cross join t1 l cross join t1 d
where o.role_name = 'Owner' 
   and l.role_name = 'Lead' 
   and d.role_name = 'Developer'

enter image description here

根据值将 SQL 列拆分为多列

Splitting SQL column into multiple columns based on value

sql-server

sql-server-2017