Question

我的数据看起来像：

OrderID CustomerID  ItemID  ItemName
10000   1234        111111  Product A
10000   1234        222222  Product B
10000   1234        333333  Product C
20000   5678        111111  Product A
20000   5678        222222  Product B
20000   5678        333333  Product C

我想在SQL Server中编写一个T-SQL查询来返回如下数据：

<Root>
  <Order>
    <OrderID>10000</OrderID>
    <CustomerID>1234</CustomerID>
    <LineItem>
      <ItemID>11111</ItemId>
      <ItemName>Product A</ItemName>
    </LineItem>
    <LineItem>
      <ItemID>22222</ItemId>
      <ItemName>Product B</ItemName>
    </LineItem>
    <LineItem>
      <ItemID>33333</ItemId>
      <ItemName>Product B</ItemName>
    </LineItem>
  </Order>
  <Order>
    <OrderID>20000</OrderID>
    <CustomerID>5678</CustomerID>
    <LineItem>
      <ItemID>11111</ItemId>
      <ItemName>Product A</ItemName>
    </LineItem>
    <LineItem>
      <ItemID>22222</ItemId>
      <ItemName>Product B</ItemName>
    </LineItem>
    <LineItem>
      <ItemID>33333</ItemId>
      <ItemName>Product B</ItemName>
    </LineItem>
  </Order>
</Root>

我尝试使用以下方法在XML中返回查询：

FOR XML PATH ('Order'), root ('Root')

但是这给了我一个Order节点，每行（总共6个），而不是每个orderId的订单节点（总共2个）。

有什么想法吗？

Answer 1

select  
    OrderID,
    CustomerID,
    (
        select 
        ItemID,
        ItemName
        from @Orders rsLineItem
        where rsLineItem.OrderID = rsOrders.OrderID
        for xml path('LineItem'), type
    )
from (select distinct OrderID, CustomerID from @Orders) rsOrders
FOR XML PATH ('Order'), root ('Root')

Answer 2

完成：这是一个没有subselect的解决方案，应该对大表执行得更快。相反，它将表格分组的次数与XML中的级别一样多，并使用GROUPING_ID标识级别（请参阅https://technet.microsoft.com/en-us/library/bb522495(v=sql.105).aspx和https://docs.microsoft.com/en-us/sql/relational-databases/xml/use-explicit-mode-with-for-xml）：

with rsOrders as (
  select '10000' OrderID, '1234' CustomerID, '111111' ItemID, 'Product A' ItemName union
  select '10000' orderId, '1234' customerID, '222222' itemID, 'Product B' ItemName union
  select '10000' orderId, '1234' customerID, '333333' itemID, 'Product C' ItemName union
  select '20000' orderId, '5678' customerID, '111111' itemID, 'Product A' ItemName union
  select '20000' orderId, '5678' customerID, '222222' itemID, 'Product B' ItemName union
  select '20000' orderId, '5678' customerID, '333333' itemID, 'Product C' ItemName 
)
select case 
         when GROUPING_ID(ItemID) = 0 then 3 
         when GROUPING_ID(OrderID) = 0 then 2 
         else 1 
         end as tag,
       case 
           when GROUPING_ID(ItemID) = 0 then 2 
         when GROUPING_ID(OrderID) = 0 then 1 
         else null
       end as parent,
       null       as 'Root!1',
       OrderID    as 'Order!2!OrderID!element', 
       CustomerID as 'Order!2!CustomerID!element', 
       ItemID     as 'LineItem!3!ItemID!element', 
       ItemName   as 'LineItem!3!ItemName!element'
  from rsOrders
 group by grouping sets ((), (OrderID, CustomerID), (OrderID, CustomerID, ItemID, ItemName))
 order by OrderID, CustomerID, ItemID, ItemName
   for xml explicit, type

SQL Server：FOR XML PATH - 嵌套/分组

2 个答案: