LINQ to “Relational” (L2R) in Visual Studio 2008 SP 1 Mike Taulty Developer & Platform Group Microsoft Ltd [email_address] http://www.miketaulty.com

Where Are We?

“ Traditional” ADO.NET Data Access App Code Customers ADO.NET DataReader Customers Command “ SELECT * FROM CUSTOMERS” DataSet

“ Traditional” ADO.NET Data Access App Code Customers ADO.NET Layer DataReader Customers Command “ SELECT * FROM CUSTOMERS” Data Object Load() Customer FirstName LastName ... Customer FirstName LastName ... Customer FirstName LastName ... Customer FirstName LastName ... ORM

Language Integrated Query from data in someDataSource join otherData in someOtherSource on keyExpr equals keyExpr ( into itemName )? let someVariable = someExpression where somePredicate orderby ( expression ( ascending | descending )?)* select expression group expression by keyExpression into itemName .NET Framework V3.5 Service Pack 1 Language Features ( C# V3 and VB V9 ) Custom Objects XML SQL Entities

LINQ is not just relational

Two Different Styles of LINQ from data in someDataSource join otherData in someOtherSource on keyExpr equals keyExpr ( into itemName )? let someVariable = someExpression where somePredicate orderby ( expression ( ascending | descending )?)* select expression group expression by keyExpression into itemName IEnumerable<T> IQueryable<T>

IEnumerable/IQueryable

LIN Q is about Query LINQ specifies a standard syntax for querying data LINQ has no standard syntax for modifying data Different API’s take a different approach LINQ to Objects has no approach – unneccessary LINQ to XML LINQ to SQL LINQ to Entities

LINQ specifies a standard syntax for querying data

LINQ has no standard syntax for modifying data

Different API’s take a different approach

LINQ to Objects has no approach – unneccessary

LINQ to XML

LINQ to SQL

LINQ to Entities

LINQ to Relational ( “L2R” ) LINQ to SQL .NET Framework V3.5 SQL Server databases – 2000, 2005, 2008 & CE Uses existing ADO.NET SQL Provider ADO.NET Entity Framework (“LINQ to Entities”) .NET Framework V3.5 Service Pack 1 Database agnostic Needs modified ADO.NET Providers Microsoft ships SQL and example Oracle provider Various 3 rd party providers in progress

LINQ to SQL

.NET Framework V3.5

SQL Server databases – 2000, 2005, 2008 & CE

Uses existing ADO.NET SQL Provider

ADO.NET Entity Framework (“LINQ to Entities”)

.NET Framework V3.5 Service Pack 1

Database agnostic

Needs modified ADO.NET Providers

Microsoft ships SQL and example Oracle provider

Various 3 rd party providers in progress

L2R – Commonality in Querying App Code Customers “ LINQ” Queryable Object DataReader Customers LINQ Query Call Execute Context GetQueryable<T>() Execute<T>() Customer FirstName LastName ... Customer FirstName LastName ... Customer FirstName LastName ... Materialise objects ADO.NET Provider Translate to SQL ORM Metadata Create

L2R – Commonality in Modifying App Code Customers “ LINQ” Context Customer FirstName LastName ... Customer FirstName LastName ... Customer FirstName LastName ... “ Create”<T>() “ Delete”<T> SaveChanges() Create Delete Update State Del Del Del Ins Upd Save ADO.NET Provider Translate to SQL ORM Metadata

L2R - Differences

LINQ to Relational

Resources

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