SQL Server 2005 The Common Language Runtime (CLR) Integration

CLR IntegrationCLR Introduction

Highlights Common type system (CTS)

Mapping of data types. Programming language Framework Just-in-time (JIT) compilers

JIT compiles intermediary language (MSIL) into native code Highly optimized for platform or device

Garbage collector Permission and policy-based security Exceptions Threading Diagnostics and profiling

CLR IntegrationCLR Diagram

Common Language Runtime Diagram

Class Loader

MSIL to NativeCompilers (JIT)

CodeManager

GarbageCollector (GC)

Security Engine Debug Engine

Type Checker Exception Manager

Thread Support COM Marshaler

Base Class Library Support

CLR IntegrationSQL Server 2005 – CLR

Run managed code within a database by using in-process assemblies

Create managed stored procedures, triggers, user-defined functions, user-defined types, and aggregates

Integration benefits: Enhanced programming model Enhanced safety and security Common development environment Performance and scalability

CLR IntegrationDeep Integration with the Database

CLR Hosting layer provides coordination Assembly Loading Memory management Security Model Reliability Threads & Fibers Deadlock detection Execution contextWindows OSWindows OS

SQL OS LayerSQL OS Layer

SQL EngineSQL Engine

HostingHostingLayerLayer

CLRCLR

VS .NET VS .NET ProjectProject

Assembly: “TaxLib.dll”

VB,C#,C++VB,C#,C++ BuildBuild

SQL ServerSQL Server

SQL Data Definition: SQL Data Definition: create create assembly … assembly … create function … create function … create create procedure … procedure … create trigger … create trigger … create create type …type …

SQL Queries: SQL Queries: select select sum(sum(tax(sal,state)tax(sal,state)) ) from Emp where county from Emp where county = ‘King’= ‘King’

Runtime hosted by SQL

(in-proc)

The Developer The Developer ExperienceExperience

CLR IntegrationAvailable Classes

Even in supported assemblies, some APIs are not available in SQL

Environment.Exit(), Console, etc. Potentially unreliable constructs disabled

No thread creation No shared state or synchronization No listening on sockets in server No finalizers

Eliminate functionality N/A to database System.Windows.Forms System.Drawing System.Web, …

CLR IntegrationSQL Server Projects in Visual Studio 2005

Project for creating managed database objects Automatically includes necessary references

System System.Data.dll

Includes templates for each object type Stored procedure Trigger User-defined function User-defined type Aggregate

Allows immediate deployment and debugging

CLR IntegrationThe System.Data.SqlServer Namespace

ClassClass DescriptionDescription

SqlContext Provides access to other objects, like a Provides access to other objects, like a connectionconnection

SqlConnection An open connection to a SQL Server An open connection to a SQL Server databasedatabase

SqlCommand Used to send a command to the database Used to send a command to the database serverserver

SqlParameter Supplies a parameter for a SqlCommand Supplies a parameter for a SqlCommand objectobject

SqlPipe Used to send results or information to the Used to send results or information to the clientclient

SqlDataReader Reads the data one row at a time, forward Reads the data one row at a time, forward onlyonly

SqlResultSet For working with flexible server-side cursorsFor working with flexible server-side cursors

SqlTransaction For providing transactional behaviorFor providing transactional behavior

SqlTriggerContext

Provides information about the trigger Provides information about the trigger actionaction

CLR IntegrationRegistering an assembly

CREATE ASSEMBLY assembly_name [ AUTHORIZATION owner_name ] FROM { < client_assembly_specifier > | < assembly_bits >

[,...n] } [ WITH PERMISSION_SET = { SAFE |

EXTERNAL_ACCESS | UNSAFE } ] < client_assembly_specifier > :: = '[\\machine_name\]share_name\[path\]manifest_file_name' < assembly_bits > :: = { varbinary_literal | varbinary_expression }

CLR IntegrationAssembly Security -PERMISSION_SET

SAFE May not access external resources: registry, file system, or network May access data using the current context but not via SQLClient or any other

data provider No thread processing

EXTERNAL_ACCESS May access external resources:

registry, file system, network, environment variables

UNSAFE May access external resources Can use SQLClient and other data providers Can use thread constructs (No restrictions; similar to extended stored procedures)

CLR Integration Meta Data of Assemblies

Cre

ate

Ass

embl

yDetails of Assembly:

Sys.assembliesAssembly source code:

Sys.assembly_filesAssembly references:

Sys.assembly_references

Other meta data information•SYS.OBJECTSSYS.OBJECTS•SYS.ASSEMBLY_MODULESSYS.ASSEMBLY_MODULES•SYS.ASSEMBLY_TYPESSYS.ASSEMBLY_TYPES

CLR IntegrationUser Defined Functions

Similar to T-SQL function Written in CLR language

Decorated with [SqlFunction] attribute in code Assembly loaded into the database Function defined from assembly

Limits on functions must be in public class cannot be in nested class method must be public and static

CLR Integration User Defined Functions -Example

public class MyFunctions {

[SqlFunction]public static SqlString GetLongDate(SqlDateTime DateVal){

// Return the date as a long stringreturn DateVal.Value.ToLongDateString();

}

}

CLR IntegrationUser Defined Functions

Properties have impact on whether or not computed column that use these functions can be indexed.

IsDeterministic = true (it always produces the same output values given the same input values

and the same database state.) DataAccess

DataAccessKind.None: Does not access data. DataAccessKind.Read: Only reads data.

SystemDataAccess SystemDataAccessKind.None: Does not access system data. SystemDataAccessKind.Read: Only reads system data.

IsPrecise = { true | false } (that indicates whether the routine involves imprecise computations such

as floating point operations. )

CLR Integration.Net Stored Procedures (1)

Capable of doing everything a T-SQL proc can do.

Uses a Shared method (static in C#) Pass parameters both ways

OUTPUT parameters should be byref (ref in C#) Return multiple result sets

CLR Integration.Net Stored Proc Can Return (2)

Numeric return code Count of rows affected by the command Scalar value Single row One or more multi row result sets A stream of XML

CLR IntegrationStored Procedure

public class ContactCode {

[SqlProcedure]public static void GetContactNames(){

SqlCommand cmd = ……. ……cmd.CommandText = "SELECT FirstName + ' ' + LastName" +

" AS [Name] FROM Person.Contact";SqlDataReader rdr = cmd.ExecuteReader();SqlPipe sp = …………..;sp.Send(rdr);

}}

CLR IntegrationCreate Sql Server Proc.

Syntax :create procedure ProcNameas external name

<assemblyname>.<classname>.<methodname>

Example :create procedure GetContactsName as external

name assemblyname.ContactCode. GetContactNames

CLR IntegrationTriggers

public class ContactCode

{[SqlTrigger(Name="ContactUpdTrg",

Target="Person.Contact", Event="FOR UPDATE")]

public static void ChangeEmail()

{SqlTriggerContext trg = SqlContext.GetTriggerContext();

CLR IntegrationWhen to use T-SQL

T-SQL better used for data access All pre-SQL Server 2005 code is written in T-SQL SQL Server 2005 adds exception handling to T-SQL

T-SQL can be faster for data access Direct access to SQL Server's internal buffers Rich, data-centric library of functions No conversion of types

CLR IntegrationFeature Comparison with T-SQL

T-SQLT-SQL CLRCLR

User User Defined Defined FunctionsFunctions

XX XX

Stored Stored ProceduresProcedures

XX XX

TriggersTriggers XX XX

User User Defined Defined TypesTypes

XX

AggregatesAggregates XX

CLR Integration Best uses of SQLCLR

Computational functions are always faster Streaming table valued functions User defined aggregates

Orders magnitude faster than server or client cursor solutions Scalar functions

Function body is compiled to native code Use managed code for:

Procedures that feature complex logic Access to the .NET Framework class library CPU intensive functions

SQLCLR GuidanceMid Tier vs. Data Tier

SQLCLR support does not mean move all business logic to server

Candidates for moving to server Centralized data validation Process large amount of data while needing a

small portion of it for application use