将 column1 转换为标题和 column2 作为行

Question

我对在 SQL 中使用 pivot 还很陌生，想尝试一下 pivot 这个。任何帮助，将不胜感激。（罗斯文数据库）

我正在尝试将姓氏置于 TotalOrders 之上。姓氏在 column1 中，总订单在 column2

lastname  TotalOrders
---------------------
Buchanan     42

Callahan    104

Davolio     123

Dodsworth    43

Fuller       96

King         72

Leverling   127

Peacock     156

Suyama       67

/*正在尝试做：*/

[lastname]   [Buchanan]  [Callahan]...

TotalOrders     42           104   ...

/这是我目前的情况。/ [代码]

SELECT lastname, COUNT(*) TotalOrders
    FROM employees join orders
    ON employees.employeeid = orders.employeeid
    GROUP BY lastname

PIVOT 
(
  COUNT(TotalOrders)
  FOR lastname IN ([Buchanan], [Callahan], [Davolio], [Dodsworth]
                  ,[Fuller], [King], [Leverling], [Peacock], [Suyama])

) AS P;

[/代码]

Answer 1

你很接近。将连接查询放在子查询中，并在数据透视表中使用 MAX（或 MIN）。

select * 
from (
    SELECT lastname, COUNT(*) TotalOrders
    FROM employees join orders
    ON employees.employeeid = orders.employeeid
    GROUP BY lastname
) t
PIVOT 
(
  MAX(TotalOrders)
  FOR lastname IN ([Buchanan], [Callahan], [Davolio], [Dodsworth]
                  ,[Fuller], [King], [Leverling], [Peacock], [Suyama])

) AS P;

将 column1 转换为标题和 column2 作为行

Pivot column1 into the headings and column2 as rows

sql

sql-server

pivot