dynamic pivot sql

Question

我想从客户表，合同支出表和合同名称表中选择数据。我的表是这个样子

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 

我想下表产生

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语句，但我需要能够动态地定义列，因为我们需要能够额外合约名称添加到数据库和客户仍然报告花

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; 

有谁知道我可以补充我的专栏dynami凯莉

Answer 1

你必须使用动态SQL构造柱为输出：

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)