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Module 3: Using XML

Module 3: Using XML. Overview. Retrieving XML by Using FOR XML Shredding XML by Using OPENXML Introducing XQuery Using the xml Data Type. Lesson 1: Retrieving XML by Using FOR XML. Introduction to the FOR XML Clause What Are RAW Mode Queries? What Are AUTO Mode Queries?

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Module 3: Using XML

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  1. Module 3:Using XML

  2. Overview • Retrieving XML by Using FOR XML • Shredding XML by Using OPENXML • Introducing XQuery • Using the xml Data Type

  3. Lesson 1: Retrieving XML by Using FOR XML • Introduction to the FOR XML Clause • What Are RAW Mode Queries? • What Are AUTO Mode Queries? • What Are EXPLICIT Mode Queries? • What Are PATH Mode Queries? • Syntax for Retrieving Nested XML • Practice: Using FOR XML

  4. Introduction to the FOR XML Clause • Extends SELECT syntax • Returns XML instead of rows and columns • Configurable to return attributes, elements, and schema • Benefits client applications that work with XML Converted to XML Database Server Client Application

  5. What Are RAW Mode Queries? • XML representation of a rowset • Contains either elements or attributes • Optional root element and row element name SELECT Cust.CustomerID CustID, CustomerType, SalesOrderID FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML RAW SELECT Cust.CustomerID CustID, CustomerType, SalesOrderID FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML RAW, ELEMENTS SELECT Cust.CustomerID CustID, CustomerType, SalesOrderID FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML RAW('Order'), ROOT('Orders') <row CustID="1" CustomerType="S" SalesOrderID="43860"/> <row CustID="1" CustomerType="S" SalesOrderID="44501"/> ... <row> <CustID>1</CustID> <CustomerType>S</CustomerType> <SalesOrderID>43860</SalesOrderID> </row>... <Orders> <Order><CustID>1</CustID><CustomerType>S</... </Order> ... </Orders>

  6. What Are AUTO Mode Queries? • XML representation of data entities • Nest data based on join precedence • Can use options such as ELEMENTS and ROOT SELECT Cust.CustomerID CustID, CustomerType, SalesOrderID FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML AUTO <Cust CustID="1" CustomerType="S"> <Order SalesOrderID="43860" /> <Order SalesOrderID="44501" /> ... </Cust> <Cust CustID="2" CustomerType="S"> ...

  7. What Are EXPLICIT Mode Queries? • Tabular representations of XML documents • Allow complete control of XML format SELECT 1 AS Tag, NULL AS Parent, SalesOrderID AS [Invoice!1!InvoiceNo], OrderDate AS [Invoice!1!Date!Element] FROM SalesOrderHeader FOR XML EXPLICIT SELECT 1 AS Tag, NULL AS Parent, SalesOrderID AS [Invoice!1!InvoiceNo], OrderDate AS [Invoice!1!Date!Element] FROM SalesOrderHeader FOR XML EXPLICIT Attribute <Invoice InvoiceNo="43659"> <Date>2001-07-01T00:00:00</Date> </Invoice> <Invoice InvoiceNo="43660">... <Invoice InvoiceNo="43659"> <Date>2001-07-01T00:00:00</Date> </Invoice> <Invoice InvoiceNo="43660">... Element

  8. What Are PATH Mode Queries? • Use XPath to specify XML format • Allow creation of nested data • Easier to use than EXPLICIT mode SELECT EmployeeID "@EmpID", FirstName "EmpName/First", LastName "EmpName/Last" FROM Person.Contact INNER JOIN Employee ON Person.Contact.ContactID = Employee.ContactID FOR XML PATH <row EmpID="1"> <EmpName> <First>Guy</First> <Last>Gilbert</Last> </EmpName> </row> ...

  9. Syntax for Retrieving Nested XML • AUTO mode produces only attributes or elements • Use inner FOR XML with TYPE clause to return xml data type • Combine EXPLICIT mode with UNION ALL SELECT Cust.CustomerID, CustomerType, SalesOrderID, Status FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML AUTO SELECT Cust.CustomerID, CustomerType, SalesOrderID, Status FROM Customer Cust JOIN SalesOrderHeader [Order] ON Cust.CustomerID = [Order].CustomerID ORDER BY Cust.CustomerID FOR XML AUTO, ELEMENTS SELECT Name CategoryName, (SELECT Name SubCategoryName FROM ProductSubCategory SubCategory WHERE SubCategory.ProductCategoryID = Category.ProductCategoryID FOR XML AUTO, TYPE, ELEMENTS) FROM ProductCategory Category FOR XML AUTO SELECT 1 AS Tag, NULL AS Parent, ... FROM SalesOrderHeader UNION ALL SELECT 2 AS Tag, 1 AS Parent, ... FROM SalesOrderDetail OD JOIN ... FOR XML EXPLICIT <Cust> <CustomerID>1</CustomerID> <CustomerType>S</CustomerType> <Order> <SalesOrderID>43860</SalesOrderID> <Status>5</Status>... <Cust CustomerID="1" CustomerType="S"> <Order SalesOrderID="43860" Status="5"/> <Order SalesOrderID="44501" Status="5"/> ... </Cust> <Invoice InvoiceNo="43659"> <Date>2001-07-01T00:00:00</Date> <LineItem ProductID="709">Bike Socks, M</LineItem> <LineItem ProductID="711">Helmet, Blue</LineItem> </Invoice>... <Category CategoryName="Accessories"> <SubCategory> <SubCategoryName>Bike Racks</SubCategoryName> </SubCategory>...

  10. Practice: Using FOR XML In this practice, you will: • Retrieve XML in RAW mode • Retrieve XML in AUTO mode • Retrieve XML in EXPLICIT mode • Retrieve XML in PATH mode

  11. Lesson 2: Shredding XML by Using OPENXML • Overview of Shredding XML Data • Stored Procedures for Managing In-Memory Node Trees • OPENXML Syntax • Syntax for Working With XML Namespaces • Practice: Using OPENXML to Shred XML

  12. Overview of Shredding XML Data Create internal tree representation by using sp_xml_preparedocument 2 Use sp_xml_removedocumentto clean up memory tree 5 Use OPENXML to retrieve rowset 3 Process (or shred) the data into tables 4 XML documentreceived from client 1

  13. Stored Procedures for Managing In-Memory Node Trees • Create tree by using sp_xml_preparedocument • Free memory by using sp_xml_removedocument CREATE PROC ProcessOrder @doc xml -- xml data AS -- Declare document handle DECLARE @hdoc integer -- Create memory tree EXEC sp_xml_preparedocument @hdoc OUTPUT, @doc -- Process Document -- Remove memory tree EXEC sp_xml_removedocument @hdoc

  14. OPENXML Syntax <Customer CustomerID="1" CustomerType="S"> <Order SalesOrderID="43860" Status="5" OrderDate="2001-08-01T00:00:00"> <OrderDetail ProductID="761" Quantity="2"/> <OrderDetail ProductID="770" Quantity="1"/> </Order> </Customer> rowpattern identifies node level Uses attributes as default SELECT * FROM OPENXML (@idoc, '/Customer/Order/OrderDetail', 1) WITH (CustomerID int '../../@CustomerID', OrderID int '../@SalesOrderID', OrderDate datetime '../@OrderDate', ProdID int '@ProductID', Quantity int) From Customer element From Order element Defaults to Quantity attribute From OrderDetail element

  15. Syntax for Working With XML Namespaces • sp_xml_preparedocument accepts namespaces • Use namespace prefix in all XPath expressions <Customer xmlns="urn:AW_NS" xmlns:o="urn:AW_OrderNS" CustomerID="1" CustomerType="S"> <o:Order SalesOrderID="43860" Status="5" OrderDate="2001-08-01T00:00:00"> <o:OrderDetail ProductID="761" Quantity="2"/> <o:OrderDetail ProductID="770" Quantity="1"/> </o:Order> </Customer> EXEC sp_xml_preparedocument @idoc OUTPUT, @doc, <ROOT xmlns:rootNS="urn:AW_NS" xmlns:orderNS="urn:AW_OrderNS"/>' SELECT * FROM OPENXML (@idoc, '/rootNS:Customer/orderNS:Order/orderNS:OrderDetail') WITH...

  16. Practice: Using OPENXML to Shred XML In this practice, you will: • Use the OPENXML function • Shred XML by using elements only • Shred XML by using attributes or elements • Shred XML by using a colpattern parameter

  17. Lesson 3: Introducing XQuery • What Is XQuery? • XQuery Basics • XQuery Expressions

  18. What Is XQuery? • Query language to identify nodes in XML /InvoiceList/Invoice[@InvoiceNo=1000] • FLWOR statements

  19. XQuery Basics Comments (: Comment text :) Sequences and QNames • Result of an XQuery expression is a sequence • All identifiers are QNames Operators if-then-else • Arithmetic comparison • General comparison • Value comparison • Node comparison • Node order comparison • Logical if ( $A eq $B ) then <result>A</result> else <result>B</result>

  20. XQuery Expressions Primary expressions Path expressions • Relative • Literals • Variable references • Function calls child::Address/child::Country • Absolute /Address/Country Sequence expressions • Construct, filter and combine sequences declare @x xml set @x = '<root> <abc></abc> <abc attrAbc="1"></abc> <abc attrAbc="2"></abc> </root>' SELECT @x.query('/root/abc[attrAbc]')

  21. Lesson 4: Using the xml Data Type • What Is the xml Data Type? • The query, value, and exist Methods • The modify Method • The nodes Method • Practice: Using the xml Data Type

  22. What Is the xml Data Type? • Native data type for XML • Internal storage structure for XML InfoSet • Use for tables, variables, or parameters • Exposes methods to query and modify XML -- usage within table definition CREATE TABLE NewTable ( Col1 int primary key, Col2 xml ) -- usage as local variable declare @data xml -- usage as parameter to stored procedure CREATE PROCEDURE SaveData(@doc xml) AS ...

  23. The query, value, and exist Methods • Usequery to return untyped XML • Usevalue to return a scalar value SELECT xmlCol.query( '<InvoiceNumbers> { for $i in /InvoiceList/Invoice return <InvoiceNo> {number($i/@InvoiceNo)} </InvoiceNo> } </InvoiceNumbers>') • Useexist to check for the existence of a specified value • Bind relational columns and variables SELECT xmlCol.value( '(/InvoiceList/Invoice/@InvoiceNo)[1]', 'int') SELECT xmlCol.exist( '/InvoiceList/Invoice[@InvoiceNo=1000]' ) SELECT Invoices.query( '<Store> {sql:column("StoreName")} </Store>')

  24. The modify Method • insertadds child nodes or siblings to an XML document • replacevalue of updates a node in the XML document • deleteremoves a node from the XML document SET @xmlDoc.modify( 'insert element salesperson {"Bill"} as first into (/InvoiceList/Invoice)[1]') SET xmlCol.modify( replace value of (/InvoiceList/Invoice/SalesPerson/text())[1] with "Ted"') SET @xmlDoc.modify( 'delete (/InvoiceList/Invoice/SalesPerson)[1]')

  25. The nodes Method • Shreds xml variables into relational data • Requires the APPLY operator with xml columns SELECT nCol.value('@ProductID', 'int') Product, nCol.value('@Quantity', 'int') Qty FROM @xmlOrder.nodes('/Order/LineItem') AS nTable(nCol) SELECT nCol.value('../@OrderID[1]', 'int') ID, nCol.value('@ProductID[1]', 'int') Prod FROM Orders CROSS APPLY OrderDoc.nodes('/Order/LineItem') AS nTable(nCol)

  26. Practice: Using the xml Data Type In this practice, you will: • Use the xml data type • Use the query, value, and exist methods • Bind relational columns • Use the modify method to insert, update, and delete XML • Use the nodes method

  27. Lab: Working With XML • Exercise 1: Mapping Relational Data and XML • Exercise 2: Storing XML Natively in the Database • Exercise 3: Using XQuery With xml Methods

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