Microsoft SQL Server 2008 R2 Unleashed- P208 pot

LISTING 47.1 ASELECT Statement That Uses FOR XML RAW with No Additional Modifiers SELECT Name, ListPrice, Color FROM Production.Product [Product] WHERE Name LIKE ‘%Chain%’ ORDER BY Name

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CHAPTER 46 SQLCLR: Developing SQL Server Objects in NET

ORDER BY assembly_id desc

go

name assembly_id permission_set

-SQLCLR 65719 UNSAFE_ACCESS

System.Configuration.Install 65705 UNSAFE_ACCESS

System.ServiceProcess 65704 UNSAFE_ACCESS

System.Web.RegularExpressions 65703 UNSAFE_ACCESS

System.Drawing.Design 65702 UNSAFE_ACCESS

Now that you have the assembly_idfor your SQLCLR project (yours will not be the same

value as shown here), you can look up its routines and classes in sys.assembly_modules:

SELECT TOP 5

name,

assembly_class as class,

assembly_method as method

FROM sys.assembly_modules am

JOIN sys.assemblies a

ON am.assembly_id = a.assembly_id

WHERE a.assembly_id = 65719

GO

name class method

-SQLCLR StoredProcedures GetSetIllustrationWebLinks

SQLCLR StoredProcedures SpTrans

SQLCLR RegexLibrary MatchAll

SQLCLR XSLT XSLTransform

SQLCLR SumPrime NULL

Notice that the class holding your UDA (SumPrime) is listed, but your UDA itself is not

listed In addition, your UDT (RegexPattern) is not listed To see everything, you

right-click SQLCLR in the Assembliesnode of the Object Browser and then select View

Dependencies

Summary

This chapter covered the development of SQLCLR code using user-defined managed

data-base objects in conjunction with ADO.NET We also reviewed advanced topics, such as

transaction control and system catalog viewing

If you attempted the examples from start to finish, you have upgraded your SQL Server

and NET programming arsenal and opened the doorway to a new world of

data-inte-grated software

In Chapter 47, “Using XML in SQL Server 2008,” we cover SQL Server’s extensive

support for XML

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Using XML in SQL

Server 2008

What’s New in Using XML in SQL Server 2008

Understanding XML

Relational Data as XML: The

FOR XML Modes

XML as Relational Data: Using

OPENXML

Using the xml Data Type

Indexing and Full-Text Indexing

ofxml Columns

SQL Server first planted its Extensible Markup Language

(XML) roots with the introduction of the FOR XMLand

OPENXMLkeywords in SQL Server 2000, right around the

time XML was growing in popularity as a markup format

with seemingly unlimited uses

With the release of SQL Server 2008, the bar has clearly

been raised for XML support in relational databases

What’s New in Using XML in SQL

Server 2008

XML and relational data may exist side by side and are

more interchangeable than ever, thanks to SQL Server’s

XML-centric features, such as the xmldata type, extensions

toFOR XML, schema storage, content validation, indexing,

XQuery support, and more

With the release of SQL Server 2008, the SQL Server team

added support for the few XML features that were

unavail-able in SQL Server 2005, including

Support for lax validation in XML schemas

Improved support for union and list types in XML

schemas

Addition of the letclause in XQuery

Enhancements to XML Data Modification Language

(DML) expressions

The introduction of these features is both vital and timely

because XML has become the standard for everything from

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CHAPTER 47 Using XML in SQL Server 2008

traditional markup for publications to business-to-business data exchange, web services,

application programming (with XAML), graphics display (with SVG), news syndication

(with RSS), and the list goes on

But before digging into the world of SQL Server XML, let’s briefly look at what XML is

Understanding XML

XML was first created as a solution to the complexity inherent in the Standard

Generalized Markup Language (SGML), the granddaddy of all structured markup

languages What you may not know is that SGML actually contains the rules that define

how to produce other markup languages, such as HTML XML is just a subset or restriction

of those rules, providing the specifications for producing markup for all kinds of content

based on a few simple conventions

XML documents are either well formed, meaning they contain a single root element that

contains every other element (or none), or valid, meaning they are well formed and all

their elements adhere to all the constraints set forth in their associated Document Type

Definition (DTD) or XML Schema Definition (XSD)

An XML document that adheres to the constraints of a particular DTD or schema is

known as an instance of that DTD or schema In some cases, an XML document is referred

to as a fragment, meaning it contains more than one root element and/or text-only nodes.

XML documents are generally made up of elements (also called tags), attributes,

instruc-tions to the applicainstruc-tions that use the document (known as processing instrucinstruc-tions),

comments, and text Despite their variation in kind, all these structures are commonly

known as nodes.

Keep in mind that there is no set list of predefined XML tags: they can be anything the

XML specialist chooses And just as HTML is considered to be an instance of SGML, the

XML content model is also itself an instance of XML

XML’s only job is to provide the specification for how a document may be structured (or

marked up) It contains no inherent information pertaining to data display or layout,

content usage, or anything else

The pages that follow provide many examples of XML, both simple and complex We tour

the many ways SQL Server can produce, store, load, and transform XML

One of the most important uses of XML is to provide a way of describing and

encapsulat-ing relational data Doencapsulat-ing so requires a mappencapsulat-ing between two basic kinds of data

struc-tures: sets and trees The techniques shown in this section thus have a single goal:

converting the columns and rows that make up the sets derived from any SELECT

state-ment into XML trees

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Note that before XML came along, selected result sets would most likely be exported to

delimited text files for consumption by disparate systems Today, most data interchange

favors the use of XML In response, developers have come to rely on XSL for

Transformations (XSLT) as a companion skill for translating XML into HTML, PDF, RTF, or

any other type of document

Let’s look at how the SELECT FOR XMLsyntax can automatically mark up relational data

in a variety of ways The simplest approach uses FOR XML RAW

RAW Mode

When specified at the end of a SELECTstatement, the keywords FOR XML RAWtell SQL

Server to generate a one-XML-element-per-row structure The FOR XMLstatement has a few

options that change its output from the default of document fragments to well-formed

documents with a slightly (compared to a few other FOR XMLoptions) reshaped structure

This is its syntax:

FOR XML RAW [ (’ElementName’) ]

[

[ , BINARY BASE64 ]

[ , TYPE ]

[ , ROOT [ (’RootName’) ]

]

[ , { XMLDATA | XMLSCHEMA [ (’TargetNameSpaceURI’) ]} ]

[ , ELEMENTS [ XSINIL | ABSENT ] ]

Listing 47.1 illustrates the XML generated by the no-option version of FOR XML RAW (Note

that all the code in this chapter relies on the AdventureWorks2008sample database.)

LISTING 47.1 ASELECT Statement That Uses FOR XML RAW with No Additional Modifiers

SELECT Name, ListPrice, Color

FROM Production.Product [Product]

WHERE Name LIKE ‘%Chain%’

ORDER BY Name

FOR XML RAW

go

This kind of XML shape is known as attribute-centric XML because each column in the

result set is mapped to an attribute rather than an element Each row is mapped to an

element named row, which holds these attributes

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Listing 47.2 illustrates how the resultant XML can be changed into an element-centric

shape, where each selected column is converted to an XML element simply through the

addition of the ELEMENTSkeyword to FOR XML RAW

LISTING 47.2 ASELECT Statement That Uses FOR XML RAW, ELEMENTS

ORDER BY Name

FOR XML RAW, ELEMENTS

go

<row>

<Name>Chain</Name>

<Color>Silver</Color>

</row>

<row>

<Name>Chain Stays</Name>

</row>

<row>

<Name>Chainring</Name>

<Color>Black</Color>

</row>

<row>

<Name>Chainring Bolts</Name>

</row>

<row>

<Name>Chainring Nut</Name>

</row>

If the tag name rowis undesirable, you can change the element name by simply adding a

string-valued parameter, in parentheses, to the RAWkeyword

Note that in contrast to FOR XML AUTO(discussed later in this chapter), in this case,

alias-ing the Production.Producttable has no effect on the output Here’s an example:

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ORDER BY Name

FOR XML RAW(‘ChainElement’), ELEMENTS

SQL Server 2008 also enables you to return NULLcolumn values in generated XML

Previously, when a NULLcolumn value was returned in the result set when using FOR XML,

the null value was simply omitted from the XML: no attribute or element was generated

at all In SQL Server 2008, by specifying the keyword XSINILafterELEMENTS, you can

ensure that all null values are represented in the XML

Note how the xsi:nil=”true”attribute is produced for elements representing null

column values In addition, SQL Server automatically adds the XML schema namespace

declaration to each node of the resulting fragment This is required under the rules of

XML because this fragment uses a Boolean attribute called nil, which is declared in the

XML schema located at the specified URL This, as well as the effect of the ELEMENTS

keyword, is illustrated in Listing 47.3

LISTING 47.3 ASELECT Statement That Uses FOR XML RAW, ELEMENTS XSINIL

SELECT TOP 1 Name, ListPrice, Color, Weight

ORDER BY Name

FOR XML RAW(‘ChainElement’), ELEMENTS XSINIL

go

<Name>Chain</Name>

</ChainElement>

Note that the XML results in Listing 47.3 happen to produce a well-formed XML

docu-ment only because a single row was selected: this one row acts as both the root of the

document and its entire content All other XML results (including all the previous listings)

encapsulating two or more rows are actually just fragments

To easily change these XML fragments to well-formed documents, you can apply the ROOT

keyword to add a root node to the output, as shown in Listing 47.4

LISTING 47.4 ASELECT Statement That Uses FOR XML RAW and the ROOT Keyword

SELECT Name, ListPrice, Color, Weight

ORDER BY Name

FOR XML RAW(‘ChainElement’), ELEMENTS XSINIL, ROOT(‘ChainDoc’)

go

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<Name>Chain</Name>

</ChainElement>

<Name>Chain Stays</Name>

</ChainElement>

<Name>Chainring</Name>

<Color>Black</Color>

</ChainElement>

<Name>Chainring Bolts</Name>

</ChainElement>

<Name>Chainring Nut</Name>

</ChainElement>

</ChainDoc>

Users (or applications) on the receiving side of RAW-produced XML may also require an

inline XML schema (XSD) or an inline XML-Data Reduced (XDR) schema Note that inline

XDR schemas are considered to be deprecated in this release

To produce these schemas, you add the XMLSCHEMAorXMLDATAkeyword to the clause The

results are too long to be listed here, but to see how these schema types differ, compare

the output of this:

ORDER BY Name

FOR XML RAW, ELEMENTS XSINIL, XMLDATA

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to the output of this:

ORDER BY Name

FOR XML RAW(‘ChainElement’),

ELEMENTS XSINIL,

ROOT(‘ChainDoc’),

XMLSCHEMA (‘urn:www-samspublishing-com:examples’)

XML schemas are discussed in further detail later in this chapter, in the section “Using

XML Schema Collections.”

NOTE

TheXMLDATAkeyword is not permitted when ROOTis specified or when a tag name

parameter has been passed to RAW(for example,RAW(‘ChainElement’))

Note also that XMLSCHEMAtakes an optional string-valued parameter, allowing you to

specify a value for the target namespace of the produced XML (for example,XMLSCHEMA

(‘urn:www-samspublishing-com:examples))

Working with Binary Columns

Even though XML is purely a text-based markup language, FOR XMLstill has the capability

to generate XML that contains data selected from binary–data-typed columns, such as

image,binary, and varbinary To do this, SQL Server base-64 encodes the data, resulting

in a long character string

To implement this in a query, you add joins from the table Production.Productto

Production.ProductProductPhotoand then to Production.ProductPhoto, which contains

thevarbinary(max)–data-typedThumbNailPhotocolumn Then you add the keywords

BINARY BASE64to the FOR XMLclause Listing 47.5 illustrates this and also shows the

schema generated by the XMLSCHEMAkeyword (Note that the base-64 character data is

truncated in the listing for brevity with the character string { }.)

LISTING 47.5 ASELECT Statement That Uses FOR XML RAW and the BINARY BASE64

Option

SELECT TOP 1 Name, ListPrice, Color, Weight, ThumbNailPhoto

JOIN Production.ProductProductPhoto PhotoJunction ON

[Product].ProductId = PhotoJunction.ProductId

JOIN Production.ProductPhoto Photo

ON Photo.ProductPhotoId = PhotoJunction.ProductPhotoId

ORDER BY Name

FOR XML RAW(‘ChainElement’),

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ELEMENTS XSINIL,

ROOT(‘ChainDoc’),

XMLSCHEMA(‘urn:www-samspublishing-com:examples’),

BINARY BASE64

go

<xsd:schema targetNamespace=”urn:www-samspublishing-com:examples”

xmlns:xsd=”http://www.w3.org/2001/XMLSchema”

xmlns:sqltypes=”http://schemas.microsoft.com/sqlserver/2004/sqltypes”

elementFormDefault=”qualified”>

<xsd:import

namespace=http://schemas.microsoft.com/sqlserver/2004/sqltypes

schemaLocation=”http://schemas.microsoft.com/sqlserver/2004/

sqltypes/sqltypes.xsd”

/>

<xsd:element name=”ChainElement”>

<xsd:complexType>

<xsd:sequence>

<xsd:element name=”Name” nillable=”1”>

<xsd:simpleType

sqltypes:sqlTypeAlias=”[AdventureWorks2008].[dbo].[Name]”>

<xsd:restriction base=”sqltypes:nvarchar” sqltypes:localeId=”1033”

sqltypes:sqlCompareOptions=”IgnoreCase IgnoreKanaType IgnoreWidth” sqltypes:sqlSortId=”52”>

<xsd:maxLength value=”50” />

</xsd:restriction>

</xsd:simpleType>

</xsd:element>

<xsd:element name=”ListPrice” type=”sqltypes:money” nillable=”1” />

<xsd:element name=”Color” nillable=”1”>

<xsd:simpleType>

<xsd:restriction base=”sqltypes:nvarchar” sqltypes:localeId=”1033”

sqltypes:sqlCompareOptions=”IgnoreCase IgnoreKanaType IgnoreWidth” sqltypes:sqlSortId=”52”>

<xsd:maxLength value=”15” />

</xsd:restriction>

</xsd:simpleType>

</xsd:element>

<xsd:element name=”Weight” nillable=”1”>

<xsd:simpleType>

<xsd:restriction base=”sqltypes:decimal”>

<xsd:totalDigits value=”8” />

<xsd:fractionDigits value=”2” />

</xsd:restriction>

</xsd:simpleType>

</xsd:element>

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<xsd:element

name=”ThumbNailPhoto” type=”sqltypes:varbinary” nillable=”1”/>

</xsd:sequence>

</xsd:complexType>

</xsd:element>

</xsd:schema>

<Name>Chain</Name>

<ThumbNailPhoto>R0lGODlhUAAxAPcAAKeamoyLj { }</ThumbNailPhoto>

</ChainElement>

</ChainDoc>

AUTO Mode

WhenRAWmode is not enough, FOR XML AUTOprovides a few more ways to shape your

XML output Its usefulness derives from its capability to produce nested XML elements

from rows derived by joining multiple tables, in contrast to the flat structure of RAWmode

TheROOTkeyword introduced earlier also applies with AUTOmode, and it is good practice

to continue to use it in your queries Like RAWmode,AUTOmode produces attribute-centric

XML by default, but you can change this by using the ELEMENTSkeyword.XSINILand

XMLSCHEMAare also applicable here, having the same effect as with RAWmode Listing 47.6

illustrates these points

LISTING 47.6 ASELECT Statement That Uses FOR XML AUTO, ELEMENTS XSINIL,

ROOT

SELECT

Color,

Offer.SpecialOfferId Id,

Product.ProductId Id,

Name,

Description [Desc],

Size

FROM Sales.SpecialOffer Offer

JOIN Sales.SpecialOfferProduct OP ON

OP.SpecialOfferId = Offer.SpecialOfferId

JOIN Production.Product Product ON

Product.ProductId = OP.ProductId

WHERE Name LIKE ‘Mountain Bike%’

FOR XML AUTO, ELEMENTS XSINIL, ROOT(‘MountainBikeSpecials’)

go

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