sqlclr programming with sql server 2005 - by andrew novick

8/8/2019 SQLCLR Programming With SQL Server 2005 - By Andrew Novick

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© 2006 Andrew Novick

SQLCLR Programming with SQL Server 2005Andrew Novick

SQLCLR Programming

with SQL Server 2005

Andrew Novick





The Subject:

What is SQLCLR programming?

Why would you use it?

Why not to use it?





Introduction ± Andrew Novick

Novick Software

± Business Application Development

± SQL Server and .Net specialization

www.NovickSoftware.com

Books:

± Transact-SQL UDFs

± SQL 2000 XML Distilled





Authorship

This presentation is based in part on material developed for the

Mini Code-Camp ³Programming SQL Server: From 2000 to

2005´ By Andrew Novick and Adam Machanic

Adam¶s Web site is:

http://www.datamanipulation.net

Andrew Novick¶s Web Site is:

http://www.NovickSoftware.com





What Is SQLCLR?

Writing code using .Net Languages that r unsinside SQL Server.

± User-Defined Functions

± Stored Procedures ± Aggregates

± User-Defined Types

± Triggers

± SSIS Packages

± Expressions and Data Providers in Reports





Why Use .Net in S2K5

Replace Extended SP¶s with a safer alternative

Replace COM automation: sp_ O A_*

Take advantage of .Net Framework classes

Run computationally intense algorithms Reuse code

Programmer productivity

Use new capabilities not available inT

-SQL ± User Defined Types

± User Defined Aggregates



© 2006 Andrew NovickSQLCLR Programming with SQL Server 2005Andrew Novick

Hosting the CLR

S2K5 is one of many CLR hosts

± Such as: ASP.Net, WinForms

Goals for CLR hosting: ± Security

± Reliability

± Performance




SQLCLR Overall Architecture

Runtime hosted within SQL Server¶s

process space

³OS´ layer provided by SQL Server¶s

scheduler, SQLOS ± Memory

± Processor

± IO Hosting enabled on a per-server basis




SQLCLR AppDomains

App Domains created per database, per assembly owner

SQL Server will restart an app domain if itdetects:

± Deadlocks

± Memory leaks

± Hung threads

± « And other abnormal conditions




CLR is Optional!

Disabled by default

You must turn it on to use it

± SQL Server 2005 Surface Area Configuration

± This script:

EXEC sp_configure 'show advanced options' , '1';

goreconfigure;

goEXEC sp_configure 'clr enabled' , '1'

goreconfigure;




Assemblies

.Net Code compiled into an IL DLL

Assemblies must be added to S2K5 with

CREATE ASSEMBLY

Bits are stored in the database¶s

sys.assembly_files table

CREATE ASSEMBLY my_assembly_name

FROM µ\\myserver\«path\MyAssembly.dll¶




Assemblies 2

Viewing Assemblies

± SQL Management Studio

± Ref lector with the SQL 2005 Browser




Assembly Security: PERMISSION_ SET

S AFE

± Allows data access, basic libraries

EXTERNAL _ACCESS

± Allows access to IO libraries

UNS AFE

± Allows access to unmanaged code




PERMISSION_ SET: Safe

May not access external resources:registry, file system, or network

May not use unmanaged code or PInvoke

May access data using the current contextbut not via SQLClient or any other data

provider

No thread processing




PERMISSION_ SET: EXTERNAL _ACCESS

May access external resources:registry, file system, network, environment

variables

May not use:

± unmanaged code

± PInvoke




PERMISSION_ SET: UNS AFE

Can do anything«

Know your code!




SQLCLR

User-Defined Functions




Overview of CLR UDFs

Two Types ± Scalar

± Table-Valued

Similar Rules

± No side effects

More f lexible ± Can use the .Net Base Classes

± Can use user created classes

± Can execute Dynamic SQL

Performance ± Similar to better than T-SQL




CLR Scalar Functions

Simple and Flexible

.Net Functions

Usef ul for encapsulating BCL f unctionality




CLR Table-Valued Functions

³Streaming´: Returns one row at time

Requires a method with:

± Returns IEnumerable

± SqlFunctionAttribute

A second method ³shreds´ the data

± FillRowMethod ± Columns defined by output parameters




CLR Table-Valued Function Lifecycle

SQL Server invokes IEnumerable method

Which returns a reference to the collection

SQL Server enumerates the collection

Enumerate() calls the FillRowMethod

± Input object is mapped to output parameters

by the




SQLCLR Stored Procedures

Can do everything that T-SQL sprocs can

± Multiple result sets

± Output Parms

± Messages ± Return Code

Can do what other SQLCLR objects can: ± C# or VB.net code




The Same Rules Apply..!

ADO.NET in-process provider makes iteasy to move code between tiers

Best practice in the application tier:

± Use T-SQL stored procedures to encapsulatedatabase data access

Best practice in the data tier (CLR stored

procedure or UDF): ± Use T-SQL stored procedures to encapsulate

database data access




ADO.NET: Sending Back Data

SqlPipe

± Send()

Result Sets (SqlDataReader)

Rows (SqlDataRecord) Messages (System.String)

± ExecuteAndSend()

Executes SqlCommand in the connected context Should probably be called SendAndExecute()




CLR Stored Procedures

Best for: ± External Data Sources

± Multiple output parameters from external datasources

± complex math/logic

Not indicated for

± single result sets ± single scalar output




SQLCLR

User Defined Aggregates




User Defined Aggregates

Aggregates scalar values into another scalar

Uses the SqlUserDefinedAggregate attribute

CREATE AGGREGATE [Product](@Value float)

Returns [float]EXTERNAL NAME

[SampleAggregate].[SampleAggregate.Product]

go

GRANT EXEC ON dbo.Product TO PUBLICgo




Possible UDAGGs

Product

CountOfNulls

BitwiseOr

Concatenation

RegExMatchCount




Impossible UDAGG

First

Last

Impossible due to possible Parallelism




User Defined Aggregate Class

public class myAggregate

{

public void Accumulate (<input-type> value){ }

public <return-type> Terminate() { }

public void Init () { }

public void Merge (myAggregate) { }

}




UDAGG: Init

Public Sub Init()

m_Accumulator = 1.0m_HasNonNull = False

End Sub

Initialize the aggregate

Reinitializes the when SQL Server

chooses to reuse it.




UDAGG: Accumulate

Public Sub Accumulate(ByVal value As SqlDouble)if value.isnull then exit sub

m_Accumulator *= value

m_HasNonNull = True

End Sub

Called once per row to be aggregated.




UDAGG: Merge

SQL Server may use multiple threads for an aggregation.

Each thread would need it¶s own instance

of the UDAGG class. Results combined by the Merge method.




UDAGG: Merge

Public Sub Merge(ByVal value As Product)

if value is nothing then exit sub

if not value.m_HasNonNull then exit subm_Accumulator *= value.m_Accumulator

m_HasNonNull = True

End Sub




UDAGG: Terminate

Public Function Terminate() As SqlDouble

if not m_HasNonNull then

return sqldouble.nullelse

Return m_Accumulatorend if

End Function

Terminate method returns the results.




Using the User Defined Aggregate

SELECT dbo.product(sample) [Three integers]

FROM ( SELECT CAST(1.0 as float) as SampleUNION ALL SELECT 3

UNION ALL SELECT 5) Numbers

(Result)

Three integers

---------------

15




Best Practices: UDAGG

Consider T-SQL alternatives

Use SQLTypes

Code efficiently

No SQL input if you can help it.

If you need data, create a cache.

Remember Parallel execution




User-DefinedT

ypes

UDT




Two Types of UDTs

Alias Types

CLR Types

Both use the CREATE TYPE statement




CLR User-Defined Types (UDTs)

Created with the .Net CLR in VB.Net or C#

New to SQL Server 2005

Example:

CREATE Assembly myAssembly FROM

µ\\server\share\myAssembly.dll

Go

CREATE TYPE myType

EXTERNAL NAME myAssembly.[myAssembly.myType]

go




Why CLR User-Defined Types

Encapsulate application logic and data inthe database.

Benefits: ± Programmer productivity

± Consistency over the long term




Steps to create a CLR UDT

± Create a Class in a .Net language (VB or C#)

± Create the ASSEMBLY database object

± CREATE TYPE statement




CL ASS or Str ucture

Class is a reference type

Str ucture is a Value type




Create your CL ASS

Required attributes:<Serializable()> _<Microsoft.SqlServer.Server.SqlUserDefinedType(Format

.Native)>

Required Interface: INullable

Required Methods:

ToStringParse




Your Class

Public and Private fields

Static (Shared in VB) and instance members




SqlUserDefinedType Attribute

Format: Native, UserDefined

IsByteOrdered

IsFixedLength

MaxByteSize

Name

ValidationMethodName




Assemblies

.Net Code compiled into an IL DLL

Assemblies must be added to S2K5 with

CREATE ASSEMBLY

Bits are stored in the database¶ssys.assembly_files table

CREATE ASSEMBLY my_assembly_name

FROM µ\\myserver\«path\MyAssembly.dll¶




CREATE TYPE statement

CREATE TYPE [ schema_name.] type_name

{

FROM base_type

[ ( precision [ , scale ] ) ][ NULL | NOT NULL ]

| EXTERNAL NAME assembly_name

[ .class_name ]

} [ ; ]




Type Name Rules

Standard Rules for identifiers.

Recommendation: Keep It Simple




TYPE Permissions

References

Execute

These apply to:

± Assembly

± Type




Using Types in SQL

CREATE T ABLE Office (id int, location GEOPOINT)

SELECT id, Location. LatitudeLocation.Longitude

FROM Office




Type Considerations

.Net value types don¶t represent NULL

System.Data.SQLTypes represent NULL

Use the SQLTypes when possible




User Defined Types

Best used for scalar types

Not ideally suitable for ³Classes´




Best Practices - UDTs

UDTs should represent scalar objects

Separate assembly to each group of UDTs

Test extensively before deployment

Keep caref ul track of the DLL¶s

± Use Source Control for them.




Summary

SQLCLR is a powerf ul new feature Advantages

± Use .Net base-class-library

± Implement Complex Code ± Interface with external resources

Cautions:

± Doesn¶t relpace T-SQL well




Andy¶s Books




Resources

Newsletter about SQL Coding

T

heme for Fall 2005 is.Net CLR Programming

http://www.novicksoftware.com/coding-in-sql/coding-in-sql-signup.htm




Download Slides and Examples

Download this presentation and samplesfrom:

http://www.novicksoftware.com/Presentations.htm

New England Visual Basic





New England Visual Basic

Professionals

Focused on VB.Net development

Meetings @ MS Waltham

± 1st Thursday - 6:15 to 8:30

Coming up: ± Febr uary ± AviCode ± ASP.Net monitoring

± March ± Adam Machanic ADO.Net 2.0

± April ± Jesse Liberty



SQLCLR Programming with SQL Server 2005

Thanks for Coming

Andrew Novick

[email protected]

http://www.NovickSoftware.com

978-440-8126

sqlclr programming with sql server 2005 - by andrew novick

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