1. XML Data in MS SQL Server Query and Modification
Steven Blundy, Duc Duong, Abhishek Mukherji, Bartlett Shappee
CS561

2. Outline Introduction XML Data Type Publishing Structure and storage
Schema, validation
Methods
Publishing
FORXML Queries

3. Approaches for XML integration to DB
Mid-tier
Bi-directional XML view
Query view using XPath
Schema-driven approach for shredding
Server-side
rowset-to-XML aggregator for XML Publishing - FOR XML
Query-driven shredding mechanism- Open XML
This talk is an insight into how SQL Server 2005 fits XML functionality into its core relational database management framework.
Along with publishing and shredding, support is required for storing XML in native form into the DB and users wish to query into XML structure itself rather than shredding into relational data.
To address this need, SQL Server 2005 adds native XML management capabilities along the functionality outlined in the introduction of this tutorial.

4. SQL SERVER 2005 XML Architecture

5. XML Storage - Native Checks Well Formedness XML Documents or Fragments
Validation is optional
XML Documents or Fragments

6. XML Storage - DB SQL BLOB Allows for utilization BLOB optimizations
Streaming
Parsing
Compression
Unicode (UTF-16) Strings - UNTYPED
Requires Conversion
XML Schema - TYPED
Encode to match schema
Much more efficient
Storing the XML data in a BLOB provides the many benfits associated with binary data
This includes the optimaztions that coming with streaming the data to and from sources, parsing over the data, and algorithms to compress the data to save space.
With in the Binary representation,
all un-typed XML data is stored in Unicode Strings, essentially similar to the original xml text data.
When an XML schema is associated with the data, we can additional benefits
the data is stored in the most efficient way, for reducing size
the data can also be optimized for parsing and no longer needs to be pre processed

7. XML Storage - The Numbers
Advantages of Binary Storage
20 to 30% Size Reduction
Faster
Limitations
2gb of stored binary per instance
Hierarchy is limited to 128 Levels
These are the simple facts about the basic XML storage:
Advantages of Binary Storage
20 to 30% Size Reduction
Faster
Limitations
2gb of stored binary per instance
Hierarchy is limited to 128 Levels

8. Storage - Schema Storage Optimization Uses the XML Infoset
Size
Processing
Uses the XML Infoset
Defined in an XMLSchemaCollection
As mentioned before the Schema promotes storage optimization
It also adheres to the XML Infoset and is stored in XMLSchemaCollectinos as we shall see

9. Validation - Schema XML Schema Collection Uses the XML Infoset
Stores 1+ XML Schemas
Identified by Name Space
Not the Same as Constraints (No Business Logic)
Metadata Entity
Certain Type are Format Constrained
i.e. Date must use ISO 8601 format
Uses the XML Infoset
Multiple Schemas can be stored in an XML Schema Collection being Identified by Name Space.
These schemas cannot be used the same way as constraingts on the XML data as they do not provide business logic
These collections are a Meta Data entity in that the only store column infromation.
Also it is important to not that in SQL Server 2005 certain ambiguous Types such as Date and Time
must adhere to specific formats
In the case of Date and Time this is the ISO 8601 format
The Xml Schema Collection also adheres to and use the XML Infoset

10. Validation - Schema Collection
CREATE XML SCHEMA COLLECTION myCollection AS
'<xsd:schema xmlns:xsd="
xmlns="
elementFormDefault="qualified"
targetNamespace="
<xsd:element name="bookstore" type="bookstoreType" />
<xsd:complexType name="bookstoreType">
<xsd:sequence maxOccurs="unbounded">
<xsd:element name="book" type="bookType" />
</xsd:sequence>
</xsd:complexType>
<xsd:complexType name="authorName">
<xsd:sequence>
<xsd:element name="first-name" type="xsd:string" />
<xsd:element name="last-name" type="xsd:string" />
</xsd:schema>'
This just an example, see that it is still entered as one string, and then parsed and handeled by the system

11. Validation - How? At Data Entry Checking Data Updated Schema
Validness checked when typed data is inserted
Checking Data
Applied using Cast
Updated Schema
Does not Require re-validation
Validation is optional feature which can be done at two points.
When a schema is created it can be used to validate current data and also any new data entery.
On the modification of a schema, it can be applied to new incoming data and does not re-validate exsisting data.

12. XML DT Methods All evaluate an XQuery Methods
query() - returns XML output
exists() - checks if expression results in nodes
nodes() - returns XML DT values
value() - returns value as SQL DT
modify() - modify XML data

13. query() & nodes() methods
Both take XQuery string
query() returns list of untyped XML nodes
Can be converted to strings
For SELECT output
nodes() returns list of typed XML nodes
All XML DT methods available
count(*) works
No converting to strings

14. exist() & value() methods
returns true if XQuery returns any nodes
value()
Takes 2 params: an XQuery & a SQL DT
Converts xml value returned by XQuery to specified SQL type

15. Example: value() Title Design Patterns
SELECT data.value(‘(/bibliograph/book/[1]/title)[1]’,
‘NVARCHAR(255)’) AS Title
FROM Test
Title
Design Patterns

16. Example: value() w/ nodes()
SELECT book.value(‘(title)[1]’,
‘NVARCHAR(255)’) AS Title
FROM Test CROSS APPLY
data.nodes(‘/bibliograph/book’) AS R(book)
Title
Design Patterns
All about XML …

17. Example: exist() Title Design Patterns All about XML …
SELECT book.value(‘(title)[1]’,
‘NVARCHAR(255)’) AS Title
FROM Test CROSS APPLY
data.nodes(‘/bibliograph/book’) AS R(book)
WHERE data.exist(‘/bibliograph/book’) = 1
Title
Design Patterns
All about XML …

18. modify() method Uses extended XQuery Used in SQL UPDATEs
insert, delete, and replace keywords
Used in SQL UPDATEs

19. Example: modify() UPDATE docs SET xCol.modify(‘ insert
<section num="2">
<title>Background</title>
</section>
after
This example shows the use of the modify() method to insert a new <section> element to the right of the <section> element whose number is 1.

20. Example 2: modify() UPDATE XmlCatalog SET Document.modify ('
declare namespace bk = "
replace value of (/bk:bookstore/bk:book with 49.99')
The following UPDATE statement replaces the <price> of a book whose ISBN is to $ The XML instance is typed with the XML schema hence the namespace declaration in the XML data modification statement.

21. XML Publishing select CustomerID as "@CustomerID",
City as "address/city",
PostalCode as "address/zip",
ContactName as "contact/name",
Phone as "contact/phone",
from Customers
for xml path('Customer'), root('Doc')

22. Additional Papers Used
XML Support in Microsoft SQL Server 2005
Shankar Pal, Mark Fussell, and Irwin Dolobowsk
XML Best Practices for Microsoft SQL Server 2005
Shankar Pal, Vishesh Parikh, Vasili Zolotov, Leo Giakoumakis, Michael Rys

23. Questions