MSDN Magazine - March 2008 - (Page 62)

Sponsored Content Getting Started with the ADO.NET Entity Framework The ADO.NET Entity Framework provides an exciting new set of features for programming against relational data stores using entities that more closely represent real-world concepts. In this article we introduce the ADO.NET Entity Framework, along with its counterpart the Entity Data Model, and walk through an example of building a simple application to query and update pastdue orders using Microsoft’s new Language Integrated Query (LINQ). Entities may exist within an EntitySet, just as rows exist within a table in a relational schema. EntitySets are defined within an EntityContainer. There may be multiple EntitySets for a particular EntityType within a single EntityContainer; for example, Employees may be partitioned into a WesternRegionEmployees EntitySet and an EasternRegionEmployees EntitySet, both of which contain instances of EmployeeType entities. The Entity Data Model The ADO.NET Entity Framework is an implementation of Microsoft’s Entity Data Model that supports flexible mapping to existing relational schema. In order to fully understand the power of The Entity Framework, it’s useful to first understand a bit about the data model on which it is built. Microsoft’s Entity Data Model provides a more convenient way for applications and services to reason about real-world concepts. Microsoft will build services, tools, and applications for programming, storing, querying, reporting, publishing, managing, and synchronizing data in terms of this data model. Based on Dr. Peter Chen’s Entity-Relationship model*, Microsoft’s Entity Data Model describes data using two basic concepts; Entities, and Relationships between Entities. LINQ to Entities and Visual Studio 2008 Visual Studio 2008 released in November of 2007 with built-in support for LINQ over in-memory collections, DataSets, XML, and the Microsoft SQL Server family of products. LINQ over Microsoft SQL Server is supported through LINQ to SQL, which provides a strongly typed experience when working directly against the schema of a Microsoft SQL Server database. The ADO.NET Entity Framework provides a similar strongly typed experience when working with an Entity Data Model that is decoupled from the storage schema through flexible mapping. The ADO.NET Entity Framework supports Microsoft SQL Server as well as other relational stores through extended ADO.NET Data Providers. Beta 3 of the ADO.NET Entity Framework is available now and includes a limited support Go-Live license. The ADO.NET Entity Framework version 1.0 will release around the middle of this calendar year as an incremental update to the .NET Framework version 3.5. Entities An entity is an instance of an EntityType (for example, a person). The EntityType describes the Properties that define the structure of the entity (for example, name, birthdate, hair color and eye color). Properties may be simple scalar types (for example, string, boolean, or integer) or may have structure described by a ComplexType (for example, StreetAddress, City, Region, and ZipCode may be grouped together into a single “Address” property). * Chen, P.P.-S.(1976). The Entity-Relationship Model – Toward a Unified View of Data. ACM Transactions on Database Systems (TODS), 1(1),9-36. Each EntityType defines a set of Key properties that uniquely identify the instance from other instances within an EntitySet (for example, social security number). EntityTypes may extend other EntityTypes through inheritance. For example, a Salesperson EntityType may extend an Employee EntityType by adding properties

Table of Contents Feed for the Digital Edition of MSDN Magazine - March 2008

MSDN Magazine - March 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Office Space Introducing ASP.NET MVC Loosen Up CI Server Performance Office Development Test Run Security Briefs Extreme ASP.NET Foundations .NET Matters {End Bracket}

MSDN Magazine - March 2008

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