1. Using XML in SQL Server and Azure SQL Database
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

2. Meet Your Instructors Pete Harris | ‏@peteatmsft
Senior Content Devloper
Various roles at Microsoft since 1995
Graeme Malcolm |
Senior Content Developer at Microsoft
Consultant, trainer, and author since SQL Server 4.2

3. Course Topics Using XML in SQL Server and Azure SQL Database
01 | Introduction to XML Data
02 | Storing and Querying XML
03 | Implementing XML Indexes
04 | Working with Typed XML
05 | Creating Relational Data from XML
06 | Creating XML from Relational Data

4. Setting Expectations Target Audience
SQL Server database developers
Anyone pursuing Microsoft certification in SQL Server
Suggested Prerequisites/Supporting Material
Querying with Transact-SQL MVA course

5. Introduction to XML Data
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

6. Module Overview What is XML? Representing Data with XML XML Namespaces
XML Support in SQL Server and Azure SQL Database

7. What is XML? Based on SGML Describes data structures and values
Commonly used by applications for:
Data interchange
Configuration
Data storage
Case-sensitive
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<items>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>

8. Representing Data with XML Basic XML Structure
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>
element
processing instruction
text
comment
shorthand syntax for closing empty elements
attribute – order is not enforced

9. An XML Document

10. Representing Data with XML Node Trees/
order id
date
customer
name
items
item
quantity
salesperson
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>

11. Representing Data with XML Documents vs Fragments
Documents are well-formed
They have a single root element
Fragments have no root element
But all elements in the fragment are well-formed
<employee id="123">
<first-name>Naomi</first-name>
<last-name>Sharp</last-name>
</employee>
<product id="561" price =" ">Mountain Bike</product>
<product id="127" price ="9.59">Water Bottle</product>

12. XML Namespaces <items>
<?xml version="1.0" encoding="ISO "?>
<o:order xmlns:o=" xmlns:s="
xmlns:c=" xmlns:p="
o:id="123456" o:date=" ">
<s:salesperson s:id="123">
<s:name>Naomi Sharp</s:name>
</s:salesperson>
<c:customer c:id="921">
<c:name>Dan Drayton</c:name>
</c:customer>
<!-- an order may contain multiple items -->
<o:items>
<o:item p:id="561" o:quantity="1"/>
<o:item p:id="127" o:quantity="2"/>
</o:items>
</o:order>
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>
<?xml version="1.0" encoding="ISO "?>
<order xmlns=" id="123456" date=" ">
<salesperson xmlns=" id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer xmlns=" id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>

13. XML Support In SQL Server and Azure SQL Database
Feature
Description
xml data type
Store XML in variables and columns
XQuery
Node-tree query language for XML
XML Indexes
Optimize XQuery performance
XSD Schemas
Enforce type validation for XML data
FOR XML clause
Generate XML from relational data
OPENXML function
Generate relational data from XML

14. XML Support Scenarios for XML in a Database
Why work with XML data in SQL Server and Azure SQL Database?
You need to share, query, and modify XML in an efficient and transacted way
You have both relational and XML data and need to have interoperability
You need to build cross-domain applications and need portability of data
Your data is sparse or you do not know the structure of your data
You want the server to guarantee that the XML is well-formed and optionally validate your data against a schema
You want to index your XML data for high query performance
You want to store and query relational data, but use XML as an interchange format

15. Introduction to XML Data
What is XML?
Representing Data with XML
XML Namespaces
XML Support in SQL Server and Azure SQL Database

16. Storing and Querying XML
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

17. Module Overview The xml Data Type XQuery Querying the xml Data Type
Modifying the xml Data Type

18. The xml Data Type Native data type for XML
Enables you to store XML documents and fragments
Used for columns, variables, or parameters
Stores XML in an internal form
When queried, semantically equivalent XML is returned

19. The xml Data Type

20. XQuery Basic Syntax Query syntax for XML Based on XPath expressions/
order id
date
customer
name
items
item
quantity
salesperson
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="268" quantity="2"/>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>
/order/salesperson/name
/order//name
/order/items/item[1]
> 1]

21. XQuery FLWOR Queries For, (Let), Where, Order By, Return
<?xml version="1.0" encoding="ISO "?>
<order id="123456" date=" ">
<salesperson id="123">
<name>Naomi Sharp</name>
</salesperson>
<customer id="921">
<name>Dan Drayton</name>
</customer>
<!-- an order may contain multiple items -->
<items>
<item id="268" quantity="2"/>
<item id="561" quantity="1"/>
<item id="127" quantity="2"/>
</items>
</order>
<item id="127" quantity="2"/>
<item id="268" quantity="2"/>
for $i in /order/items/item
where > 1
order by
return $i

22. Querying the xml Data Type
The xml data type exposes methods support XQuery expressions
query (xquery): Returns XML node(s)
value (xquery, datatype): Returns a scalar value
exist (xquery): Returns 1 (True) or 0 (False) to indicate existence of specified node
nodes (xquery) AS table (column): Returns a rowset of XML nodes
Often used with CROSS APPLY

23. Querying the xml Data Type

24. Modifying the xml Data Type
Use the modify method:
modify (insert … into xquery)
modify (replace xquery with …)
modify (delete xquery)
Note: When modifying XML in a table, the modify method is called in the SET clause of an UPDATE statement – regardless of the type of operation!

25. Modifying the xml Data Type

26. Storing and Querying XML
The xml Data Type
XQuery
Querying the xml Data Type
Modifying the xml Data Type

27. Implementing XML Indexes
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

28. Module Overview Introduction to XML Indexes Primary XML Index
Secondary XML Indexes

29. Introduction to XML Indexes
XML data can be slow to access
Node tree is created for each query
XML indexes can help with query performance
Pre-defined node tree
Indexes contain details of:
Nodes
Values
Paths /
order id
date
customer
name
items
item
quantity
salesperson
Indexes are used in SQL Server to improve the performance of queries. XML indexes are used to improve the performance of XQuery-based queries.
Many systems query XML data directly as text. This can be very slow, particularly if the XML data is large. You saw earlier how XML data is not directly stored in a text format in SQL Server. For ease of querying, it is broken into a form of object tree that makes it easier to navigate in memory.
Rather than having to create these object trees as required for queries, which is also a relatively slow process, it is possible to define XML indexes. An XML index is rather like a copy of an XML object tree that is saved into the database for rapid reuse.
It is important to note that XML indexes can be quite large compared to the underlying XML data. Relational indexes are often much smaller than the tables on which they are built, but it is not uncommon to see XML indexes that are larger than the underlying data.
You should also consider alternatives to XML indexes. Promoting a value that is stored within the XML to a persisted calculated column would make it possible to use a standard relational index to quickly locate the value.

30. Primary XML Index
Provides a persisted node tree in an internal format that is used to speed access to elements and attributes within the XML
Requires a clustered primary key on the table
CREATE PRIMARY XML INDEX XML_Order_Items
ON Sales.Order (Items);
The primary XML index basically provides a persisted object tree in an internal format. The tree has been formed from the structure of the XML, is used to speed up access to elements and attributes within the XML, and avoids the need to read the entire XML document for every query. Before you can create a primary XML index on a table, the table must have a clustered primary key.

31. Secondary XML Indexes
Can only be created after a primary XML index has been created
You can create three types of secondary indexes to help resolve specific XQuery expressions rapidly:
PROPERTY – Optimized for retrieving multiple values in query method calls
VALUE – Optimized for retrieving single values in value method calls
PATH – Typically used by the exist method
Most of the querying benefit comes from primary XML indexes, but SQL Server also enables the creation of three types of secondary XML index. These secondary indexes are each designed to speed up a particular type of query. There are three forms of query that they help with: PATH, VALUE, and PROPERTY:
A PATH index helps to decide whether a particular path to an element or attribute is valid. It is typically used with the exist() XQuery method.
A VALUE index helps to obtain the value of an element or attribute.
A PROPERTY index is used when retrieving multiple values through PATH expressions.
You can only create a secondary XML index after a primary XML index has been established.
When you are creating the secondary XML index, you need to reference the primary XML index.
CREATE XML INDEX XML_Order_Items_Property
ON Sales.Order (Items)
USING XML INDEX XML_Order_Items FOR PROPERTY;

32. Using XML Indexes

33. Implementing XML Indexes
Introduction to XML Indexes
Primary XML Index
Secondary XML Indexes

34. Working with Typed XML
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

35. Module Overview XML Schemas XML Schema Collections
Untyped XML vs Typed XML
Storing Fragments or Documents

36. XML Schema XML schema describes the structure of an XML document
XML schema language is also called XML Schema Definition (XSD)
An XML schema provides the following:
Validation constraints
Data type information
Information about types of attributes and elements

37. Validating XML with an XML Schema

38. XML Schema Collections
You can optionally associate XSD schemas with an xml data type through an XML schema collection
The XML schema collection:
Stores the imported XML schemas
Validates xml data type instances
Types the XML data as it is stored in the database

39. Untyped XML vs. Typed XML
Use the untyped xml data type when:
You do not have a schema for your XML data
You have schemas, but don’t want the server to validate data (there is significant impact on a server performing validation)
Use the typed xml data type when:
You have schemas and want the server to validate XML data
You want to take advantage of storage and query optimizations based on type information
You want to take advantage of type information during compilation of your queries

40. Storing Fragments or Documents
The xml data type stores content by default (including fragments)
You can specify the DOCUMENT keyword to prevent storage of fragments

41. Using XML Schema Collections

42. Working with Typed XML XML Schemas XML Schema Collections
Untyped XML vs Typed XML
Storing Fragments or Documents

43. 05 | Creating Relational Data from XML
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

44. Module Overview Options for Shredding XML The nodes Method
sp_xml_preparedocument and sp_xml_removedocument
OPENXML
OPENXML with Namespaces
XML Metadata Properties

45. Options for Shredding XML
The nodes method of the xml data type
The OPENXML statement
<?xml version="1.0“ ?>
<order id="123456"> …
</order>
SELECT t.n.value(…)
AS t(n)
<?xml version="1.0“ ?>
<order id="123456"> …
</order>
sp_xml_preparedocument
SELECT *
FROM OPENXML
sp_xml_removedocument

46. Relative path to value node
The nodes Method
Relative path to value node
SELECT 'int') AS OrderID,
'date') AS OrderDate,
OrderTable.OrderXml.value('./customer[1]/name[1]', 'nvarchar(25)') AS Customer
AS OrderTable(OrderXml);
Context node
Use nodes in the FROM clause to specify a context node
Creates a row for each instance of that node
Use value in the SELECT clause to extract values from relative nodes (using XPath expressions)

47. Shredding XML with the nodes Method

48. sp_xml_preparedocument and sp_xml_removedocument
Use sp_xml_preparedocument to create a node tree
Use sp_xml_removedocument to release memory
int;
EXEC
EXEC

49. OPENXML
Handle returned by sp_xml_preparedocument
Context node
SELECT * FROM 'order', 1)
WITH (id int,
date date,
customerid varchar(25) 'customer/name');
Flags:
0: attribute-centric
1: attribute-centric
2: element-centric
3 (1+2): attributes and elements
Explicit path to non-default node
Note that the rowset schema in the WITH clause can be a table name if the flags enables all nodes to be located without an explicit column pattern.
Specify document handle, row pattern to context node, and flags to indicate default centricity
Specify rowset schema and explicit column patterns in the WITH clause

50. Using OPENXML

51. OPENXML with Namespaces
Specify namespace and prefix in sp_xml_preparedocument
Additional parameter with <root> tag
Prefix namespace in row and column patterns
EXEC
'<root xmlns:awo="
SELECT * FROM 'awo:order', 1)
WITH (id int,
date date,
customer varchar(25) 'awo:customer/awo:name');

52. Using OPEN XML with a Namespace

53. XML Metadata Properties
Retrieving XML Metadata properties
as a column pattern
Creating overflow columns
Use Flag + 8, retrieve non-mapped XML
Creating an edge table
Omit flags and WITH clause

54. Using Metadata Columns

55. Creating Relational Data from XML
Options for Shredding XML
The nodes Method
sp_xml_preparedocument and sp_xml_removedocument
OPENXML
OPENXML with Namespaces
XML Metadata Properties

56. 06 | Creating XML from Relational Data
Pete Harris | Senior Content Developer, Microsoft
Graeme Malcolm | Senior Content Developer, Microsoft

57. Module Overview The FOR XML Clause RAW Mode AUTO Mode EXPLICIT Mode
PATH Mode
Using Namespaces with FOR XML

58. The FOR XML Clause Extends SELECT syntax
Returns XML instead of rows and columns
Is configurable to return attributes, elements, and the schema

59. RAW Mode Returns an XML representation of a rowset
Results can be element- or attribute-centric
Specify an optional root element and row element name
SELECT c.CustomerID AS CustID, c.CompanyName,
soh.SalesOrderID, soh.OrderDate, soh.TotalDue
FROM SalesLT.Customer AS c
INNER JOIN SalesLT.SalesOrderHeader AS soh
ON c.CustomerID = soh.CustomerID
ORDER BY c.CustomerID
FOR XML RAW('Order'), ROOT('Orders'), ELEMENTS;

60. Using RAW Mode

61. AUTO Mode Creates nested child-elements for joined tables
Elements are named to match table (or alias)
Results can be element- or attribute-centric
Specify an optional root element
SELECT [Order].SalesOrderID, [Order].OrderDate,
[LineItem].ProductID, [LineItem].OrderQty,
FROM Sales.SalesOrderHeader AS [Order]
INNER JOIN Sales.SalesOrderDetail AS LineItem
ON LineItem.SalesOrderID = [Order].SalesOrderID
ORDER BY [Order].SalesOrderID
FOR XML AUTO, ROOT('Orders'), ELEMENTS;

62. Using AUTO Mode

63. EXPLICIT Mode Enables tabular representation of XML documents
Enables complete control of the XML structure
SELECT 1 AS Tag, NULL AS Parent,
SalesOrderID AS [Invoice!1!InvoiceNo],
OrderDate AS [Invoice!1!Date],
CustomerID AS [Invoice!1!CustomerID!Element],
TotalDue AS [Invoice!1!TotalDue!Element]
FROM SalesLT.SalesOrderHeader
WHERE SalesOrderID = 71774
FOR XML EXPLICIT;

64. Using EXPLICIT Mode

65. PATH Mode Uses XML Path Language (X Path) to specify XML format
Enables the creation of nested data and specifies what should be exposed as an element or an attribute
Easier to use than EXPLICIT mode
SELECT o.SalesOrderID AS o.OrderDate AS
o.CustomerID AS c.CompanyName AS 'customer',
o.TotalDue AS 'totaldue'
FROM SalesLT.SalesOrderHeader AS o
JOIN SalesLT.Customer AS c
ON o.CustomerID = c.CustomerID
WHERE SalesOrderID = 71774
FOR XML PATH('invoice');

66. Using PATH Mode

67. Using Namespaces with FOR XML
Supported only for RAW, AUTO, and PATH modes
Specify a namespace and prefix
Explicitly name elements and attributes with prefix
WITH XMLNAMESPACES (' AS ord)
WITH XMLNAMESPACES (' AS ord)
SELECT SalesOrderID AS 'ord:SalesOrderID',
OrderDate AS 'ord:OrderDate',
CustomerID AS 'ord:CustomerID',
TotalDue AS 'ord:TotalDue'
FROM SalesLT.SalesOrderHeader
WHERE SalesOrderID = 71774
FOR XML RAW('ord:Order'), ELEMENTS;

68. Using Namespaces with FOR XML

69. Creating XML from Relational Data
The FOR XML Clause
RAW Mode
AUTO Mode
EXPLICIT Mode
PATH Mode
Using Namespaces with FOR XML

70. Using XML in SQL Server and Azure SQL Database
01 | Introduction to XML Data
02 | Storing and Querying XML
03 | Implementing XML Indexes
04 | Working with Typed XML
05 | Creating Relational Data from XML
06 | Creating XML from Relational Data