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SQL Server 2005 The Common Language Runtime (CLR) Integration Presented by Tarek Ghazali IT Technical Specialist Microsoft SQL Server MVP Web Development MCP LebDev Vice President © 2006 Tarek Ghazali. All rights reserved. CLR Integration CLR 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 Integration CLR Diagram Class Library Support CommonBase Language Runtime Diagram Thread Support COM Marshaler Type Checker Exception Manager Security Engine Debug Engine MSIL to Native Compilers (JIT) Code Manager Class Loader Garbage Collector (GC) CLR Integration SQL Server 2005 – CLR Run managed code within a database by using in-process assemblies Create managed stored procedures, triggers, user-defined functions, userdefined types, and aggregates Integration benefits: – – – – Enhanced programming model Enhanced safety and security Common development environment Performance and scalability CLR Integration Deep Integration with the Database SQL Engine CLR Hosting Layer SQL OS Layer Windows OS CLR Hosting layer provides coordination – – – – – – – Assembly Loading Memory management Security Model Reliability Threads & Fibers Deadlock detection Execution context The Developer Experience VB,C#,C++ VS .NET Project Build Runtime hosted by SQL (in-proc) SQL Queries: select sum(tax(sal,state)) from Emp where county = ‘King’ Assembly: “TaxLib.dll” SQL Data Definition: create assembly … create function … create procedure … create trigger … create type … SQL Server CLR Integration Available Classes Even in supported assemblies, some APIs are not available in SQL – Environment.Exit(), Console, etc. Potentially unreliable constructs disabled – – – – No No No No thread creation shared state or synchronization listening on sockets in server finalizers Eliminate functionality N/A to database – System.Windows.Forms – System.Drawing – System.Web, … CLR Integration SQL 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 Integration The System.Data.SqlServer Namespace Class Description SqlContext Provides access to other objects, like a connection SqlConnection An open connection to a SQL Server database SqlCommand Used to send a command to the database server SqlParameter Supplies a parameter for a SqlCommand object SqlPipe Used to send results or information to the client SqlDataReader Reads the data one row at a time, forward only SqlResultSet For working with flexible server-side cursors SqlTransaction For providing transactional behavior SqlTriggerContext Provides information about the trigger action CLR Integration Registering 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_nam e' – < assembly_bits > :: = – { varbinary_literal | varbinary_expression } CLR Integration Assembly 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 Assembly Create Meta Data of Assemblies Details of Assembly: Assembly source code: Sys.assembly_files Sys.assemblies Other meta data information •SYS.OBJECTS •SYS.ASSEMBLY_MODULES •SYS.ASSEMBLY_TYPES Assembly references: Sys.assembly_references CLR Integration User 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 string return DateVal.Value.ToLongDateString(); } } CLR Integration User 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 Integration Stored 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 Integration Create Sql Server Proc. Syntax : create procedure ProcName as external name <assemblyname>.<classname>.<methodn ame> Example : create procedure GetContactsName as external name assemblyname.ContactCode. GetContactNames CLR Integration Triggers public class ContactCode { [SqlTrigger(Name="ContactUpdTrg", Target="Person.Contact", Event="FOR UPDATE")] public static void ChangeEmail() {SqlTriggerContext trg = SqlContext.GetTriggerContext(); DEMO CLR Integration When 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 TSQL 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 Integration Feature Comparison with T-SQL User Defined Functions Stored Procedures Triggers User Defined Types Aggregates T-SQL X CLR X X X X X X X 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 Guidance Mid 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 Resources & Questions Microsoft Resources: – msdn.microsoft.com/sqlserver/ – www.microsoft.com/sql/community Contact me: – [email protected] – www.sqlmvp.com (will be available soon) Download Presentation : – www.lebdev.net Thanks.