dynamic pivot sql

Question

我想從客戶表，合同支出表和合同名稱表中選擇數據。我的表是這個樣子

Customers 
CustomerID CustomerName Address   etc 
1   "ABC Corp" "123 Here Ave" 
2   "Acme Corp" "101 Lets Ave" 

ContractTypes 
ContractTypeID ContractName 
1    "Website Hosting" 
2    "Domain Hosting" 
3    "Email Hosting" 

ServiceSpend 
ServiceSpendID ContractTypeID CustomerID Spend 
1    2    1   5.99 
2    1    1   5.99 
3    1    2   9.99 

我想下表產生

CustomerID CustomerName Address   DomainHosting WebsiteHosting 
1   "ABC Corp" "123 Here Ave" 9.99   5.99 

目前我有工作了下面的SQL語句，但我需要能夠動態地定義列，因爲我們需要能夠額外合約名稱添加到數據庫和客戶仍然報告花

select * 
from 
(
SELECT   
Customers.CustomerID, Customers.ContactName, Customers.Address,        ContractTypes.ContractName AS ContractName, ServiceSpend.Spend 
FROM    
Customers INNER JOIN 
ServiceSpend ON Customers.CustomerID = ServiceSpend.CustomerID 
INNER JOIN 
ContractTypes ON ServiceSpend.ContractTypeID = ContractTypes.ContractTypeID 
) src 
pivot 
(
sum(spend) 
    for ContractName in ([Website Hosting],[Domain Hosting])) piv; 

有誰知道我可以補充我的專欄dynami凱莉

Answer 1

你必須使用動態SQL構造柱爲輸出：

DECLARE @Columns VARCHAR(1000) = STUFF((
    SELECT ',[' + ContactName + ']' 
    FROM ContactTypes 
    FOR XML PATH('') 
    ),1,1,'') 
DECLARE @Sql VARCHAR(1000) = ' 
    SELECT * 
    FROM (
     SELECT   
      Customers.CustomerID, 
      Customers.ContactName, 
      Customers.Address, 
      ContractTypes.ContractName, 
      ServiceSpend.Spend 
     FROM Customers 
      INNER JOIN ServiceSpend 
       ON Customers.CustomerID = ServiceSpend.CustomerID 
      INNER JOIN ContractTypes 
       ON ServiceSpend.ContractTypeID = ContractTypes.ContractTypeID 
     ) SRC 
     PIVOT (SUM(Spend) FOR ContractName IN (' + @Columns + ')) piv;' 
EXEC (@Sql)