LINQ to SQL tools in Visual Studio

LINQ to SQL was the first object-relational mapping technology released by Microsoft. It works well in basic scenarios and continues to be supported in Visual Studio, but it’s no longer under active development. Use LINQ to SQL when maintaining a legacy application that’s already using it, or in simple applications that use SQL Server and do not require multi-table mapping. In general, new applications should use the Entity Framework when an object-relational mapper layer is required.

Install the LINQ to SQL tools

In Visual Studio, you create LINQ to SQL classes that represent SQL tables by using the Object Relational Designer (O/R Designer). The O/R designer is the UI for editing .dbml files. Editing .dbml files with a designer surface requires the LINQ to SQL tools which are not installed by default as part of any of the workloads of Visual Studio.

To install the LINQ to SQL tools, start the Visual Studio installer, choose Modify, then select the Individual Components tab, and then select LINQ to SQL tools under the Code Tools category.

What is the O/R Designer

The O/R Designer has two distinct areas on its design surface: the entities pane on the left, and the methods pane on the right. The entities pane is the main design surface that displays the entity classes, associations, and inheritance hierarchies. The methods pane is the design surface that displays the DataContext methods that are mapped to stored procedures and functions.

The O/R Designer provides a visual design surface for creating LINQ to SQL entity classes and associations (relationships) that are based on objects in a database. In other words, the O/R Designer creates an object model in an application that maps to objects in a database. It also generates a strongly-typed DataContext that sends and receives data between the entity classes and the database. The O/R Designer also provides functionality to map stored procedures and functions to DataContext methods for returning data and populating entity classes. Finally, the O/R Designer provides the ability to design inheritance relationships between entity classes.

原文地址：http://www.cnblogs.com/chucklu/p/16922065.html