Using Nested FOR XML Queries in ASP.NET
In this example, an ASP.NET application returns XML to a browser by executing a stored procedure in SQL Server. The stored procedure generates XML using nested queries. A similar SELECT statement is shown in the topic Generating Siblings by Using a Nested AUTO Mode Query. This example demonstrates one way to use nested FOR XML queries to generate element-centric XML in SQL Server.
Example
CREATE PROC GetSalesOrderInfo AS
SELECT
(SELECT top 2 SalesOrderID, SalesPersonID, CustomerID,
(select top 3 SalesOrderID, ProductID, OrderQty, UnitPrice
from Sales.SalesOrderDetail
WHERE SalesOrderDetail.SalesOrderID = SalesOrderHeader.SalesOrderID
FOR XML AUTO, TYPE)
FROM Sales.SalesOrderHeader
WHERE SalesOrderHeader.SalesOrderID = SalesOrder.SalesOrderID
for xml auto, type),
(SELECT *
FROM (SELECT SalesPersonID, EmployeeID
FROM Sales.SalesPerson, HumanResources.Employee
WHERE SalesPerson.SalesPersonID = Employee.EmployeeID) As SalesPerson
WHERE SalesPerson.SalesPersonID = SalesOrder.SalesPersonID
FOR XML AUTO, TYPE, ELEMENTS)
FROM (SELECT SalesOrderHeader.SalesOrderID, SalesOrderHeader.SalesPersonID
FROM Sales.SalesOrderHeader, Sales.SalesPerson
WHERE SalesOrderHeader.SalesPersonID = SalesPerson.SalesPersonID
) as SalesOrder
ORDER BY SalesOrder.SalesOrderID
FOR XML AUTO, TYPE
GO
This is the .aspx application. It executes the stored procedure and returns XML in the browser:
<%@LANGUAGE=C# Debug=true %>
<%@import Namespace="System.Xml"%>
<%@import namespace="System.Data.SqlClient" %><%
Response.Expires = -1;
Response.ContentType = "text/xml";
%>
<%
using(System.Data.SqlClient.SqlConnection c = new System.Data.SqlClient.SqlConnection("Data Source=server;Database=AdventureWorks;Integrated Security=SSPI;"))
using(System.Data.SqlClient.SqlCommand cmd = c.CreateCommand())
{
cmd.CommandText = "GetSalesOrderInfo";
cmd.CommandType = CommandType.StoredProcedure;
cmd.Connection.Open();
System.Xml.XmlReader r = cmd.ExecuteXmlReader();
System.Xml.XmlTextWriter w = new System.Xml.XmlTextWriter(Response.Output);
w.WriteStartElement("Root");
r.MoveToContent();
while(! r.EOF)
{
w.WriteNode(r, true);
}
w.WriteEndElement();
w.Flush();
}
%>
To test the application
Create the stored procedure in the AdventureWorks database.
Save the .aspx application in the c:\inetpub\wwwroot directory (GetSalesOrderInfo.aspx).
Execute the application (https://server/GetSalesOrderInfo.aspx).