透视数据

Question

这是我的SQL语句

select  id , name, type,  value  from table1 a
INNER JOIN table2 b on a.id = b.id
where  b.type in ('display','contact','ship')

产生以下结果的

ID  name     type           value
5   test     display        display1
5   test     contact        contact1
5   test     ship           ship1
6   test2    display        display2
6   test2    contact        contact2
6   test2    ship           ship2

我需要以这种

的方式获得结果

id  name   display   contact   ship
5   test   display1  contact1 ship1
6   test2  display2  contact2 ship2

我尝试了这个解决方案：https://stackoverflow.com/a/6849706/2645738，但它给了我相同的结果（每个数据3行）。这就像我需要按ID和名称分组，但不知道如何以列显示，联系和发布。

请你帮助我。

Answer 1

有必要使用PIVOT您也可以使用简单的case表达式

SELECT ID,
      Name,
       MAX(CASE([type]) WHEN 'display' THEN value END) [display],
       MAX(CASE([type]) WHEN 'contact' THEN value END) [contact],
       MAX(CASE([type]) WHEN 'ship' THEN value END) [ship]
FROM <table> GROUP BY ID, Name

结果：

ID  Name    display     contact     ship
5   test    display1    contact1    ship1
6   test2   display2    contact2    ship2

Answer 2

此查询应该为您提供所需的结果：

select  a.id , a.name, 
        max(case when b.type = 'display' then value end) as display,
        max(case when b.type = 'contact' then value end) as contact,
        max(case when b.type = 'ship' then value end) as ship
from table1 a
INNER JOIN table2 b on a.id = b.id
where  b.type in ('display','contact','ship')
group by a.id, a.name

Answer 3

这为我工作

WITH T
AS
(
    SELECT
      id , 
      name, 
      type,  
      value  
      FROM table1 a
        INNER JOIN table2 b 
          ON a.id = b.id
        WHERE  b.type in ('display','contact','ship')
)
SELECT
  *
  FROM T
  PIVOT
  (
    MAX([Value])
    FOR
    [Type] IN
    (
        [display],[Contact],[Ship]
    )
  )PVT

检查SQLFiddle

Answer 4

如果您需要PIVOT：

DECLARE @DataSource TABLE
(   
    [id] TINYINT
   ,[name] VARCHAR(12)
   ,[type] VARCHAR(12)
   ,[value] VARCHAR(12)
);

INSERT INTO @DataSource ([id], [name], [type], [value])
VALUES (5, 'test', 'display', 'display1')
      ,(5, 'test', 'contact', 'contact1')
      ,(5, 'test', 'ship', 'ship1')
      ,(6, 'test2', 'display', 'display2')
      ,(6, 'test2', 'contact', 'contact2')
      ,(6, 'test2', 'ship',  'ship2');

SELECT *
FROM @DataSource
PIVOT
(
    MAX([value]) FOR [type] IN ([display], [contact], [ship])
) PVT;

Answer 5

var n interface{} = 2
var pn = &n
var pf = (*int64)(unsafe.Pointer(pn))
fmt.Println(pf)
fmt.Println(pn)
fmt.Println(*pn) // 2
fmt.Println(*pf) // not 2
*pf = 9
fmt.Println(*pn) //error invalid memory address or nil pointer dereference
fmt.Println(*pf) // 9