Using LINQ to SQL - Part 1
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by Scott Guthrie
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What Is LINQ to SQL?

LINQ to SQL is an O/RM (object relational mapping) implementation that ships in the .NET Framework "Orcas" release, and which allows you to model a relational database using .NET classes.  You can then query the database using LINQ, as well as update/insert/delete data from it.

LINQ to SQL fully supports transactions, views, and stored procedures.  It also provides an easy way to integrate data validation and business logic rules into your data model.

Modeling Databases Using LINQ to SQL:

Visual Studio "Orcas" ships with a LINQ to SQL designer that provides an easy way to model and visualize a database as a LINQ to SQL object model.  My next blog post will cover in more depth how to use this designer (you can also watch this video I made in January to see me build a LINQ to SQL model from scratch using it). 

Using the LINQ to SQL designer I can easily create a representation of the sample "Northwind" database like below:

Figure 1

My LINQ to SQL design-surface above defines four entity classes: Product, Category, Order and OrderDetail.  The properties of each class map to the columns of a corresponding table in the database.  Each instance of a class entity represents a row within the database table.

The arrows between the four entity classes above represent associations/relationships between the different entities.  These are typically modeled using primary-key/foreign-key relationships in the database.  The direction of the arrows on the design-surface indicate whether the association is a one-to-one or one-to-many relationship.  Strongly-typed properties will be added to the entity classes based on this.  For example, the Category class above has a one-to-many relationship with the Product class.  This means it will have a "Categories" property which is a collection of Product objects within that category.  The Product class then has a "Category" property that points to a Category class instance that represents the Category to which the Product belongs.

The right-hand method pane within the LINQ to SQL design surface above contains a list of stored procedures that interact with our database model.  In the sample above I added a single "GetProductsByCategory" SPROC.  It takes a categoryID as an input argument, and returns a sequence of Product entities as a result.  We'll look at how to call this SPROC in a code sample below.

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User Comments

Title: images not visible   
Name: Dhriti
Date: 2013-02-06 6:02:23 AM
images are not visible.
Title: Image Not Visible   
Name: Manish Prasad
Date: 2012-09-04 1:29:48 AM
Images are not Visible in the Article(, Please Do the Needful

Title: thanks buddy   
Name: pravy
Date: 2009-12-30 6:54:36 AM
very help full ..... upload some more articles
Title: Developer 1   
Name: SL
Date: 2009-09-29 7:21:21 AM
Good Article
Title: Developer   
Name: SL
Date: 2009-05-11 10:16:51 AM
Very short and simple understanding article for a novice. XCellent..

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