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Adding the Linq to SQL ORM to your .NET project

written by schipps on Monday, May 25 2009

I am working on a new personal project (I mentioned it in my videocast), I am building it in MVC, since it is a small project I wanted an easy to use and implement ORM. I chose LINQ to SQL after hearing several good things. It has been a real breeze to set up and use. So, without further ado, I have put together a tutorial on how to set up LINQ-TO-SQL.



First add a new Linq to SQL class to your project. Since I'm using MVC, I'm putting my Linq to SQL classes in my Model folder. However, you can put them wherever you want. When I add the classes I get the Object Relational designer telling me to drag over items from my server explorer to map them.


Now you need to add your SQL server to your project's Server Explorer. Right click on data connections and go to add a new connection.  Put in the ODBC info for your server, and make sure to test your connection before closing. Now, if you expand your tables all you have to do is drag them over to the OR Designer.

You can very easily add relationships to your objects. I'm not sure if that would automatically happen if they are related in the DB. Someone will need to try and let me know. In order to add a relationship you right click on one of your tables, click "Add" and choose "Relationship." You can then specify the parent and child tables as well as what columns hold the relationship.


Next I'm going to build an interface to list my methods that I'm going to build to deal with my objects quickly. As you can see, mine are specific to my application, but I think they will be helpful to you anyway.



To create these methods, first I'm going to create an instance of the Data Context that was created with my .dbml. Then I'm going to use LINQ to query my objects for me and return them. I'm just making a basic Save method, and some small queries that I think I will need.


There you have it. That's how easy it is. I KNOW! You can download my source here. Now we have my model set up we can move to the rest of our MVC for web forms developers series. Stay tuned!!

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11 Comments

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Comments

  • Lee Dumond on on 5.25.2009 at 10:36 AM

    Lee Dumond avatar

    Good job Sara! To answer your question, yes. The O/R Designer will automatically pick up any FK relationships defined in the DB. In fact, that is probably the better way to go -- in case you decide to go with NH or EF at some later point, the relationships will already be there for you.

  • erik_ on on 5.25.2009 at 2:26 PM

    erik_ avatar

    Great article!

    Did you know that LINQ to SQL is placed into maintenance mode? The Entity framework will be the recommended solution for data access in .NET 4.0.

  • Lee Dumond on on 5.25.2009 at 7:18 PM

    Lee Dumond avatar

    @erik -- L2S is a perfectly good solution, and it's not nearly as half-baked as the EF 1.0 is right now. Wouldn't even consider it until 2.0 comes out...

  • Dmitry on on 5.26.2009 at 10:43 AM

    Dmitry avatar

    Good article. It is easy to understand and to the point. It is always better to make relationships on the database level for data integrity reasons.

    Here is a couple of suggestions. You probably want to implement IDisposable for the CapsuleData class and dispose the context because it implements the IDisposable interface. It would not hurt to make the context variable read-only.

  • schipps on on 5.26.2009 at 11:13 AM

    schipps avatar

    Dmitry - I am a lazy developer who usually does my DB relationships right before production, lol, I trust myself with my data but not my users. Kids - don't try this at home!!!

    Good call on the IDisposable. Thanks.

  • Craig on on 6.10.2009 at 11:09 AM

    Craig avatar

    I find linq to sql to be a little bit of evil. You are using your database schema as your model objects. this seems crazy to me. In my mind i should model my domain first, then figure out how it maps to a 2d data schema. further, i'm not sure layer constraints can ever be met using this tool, you'll pretty much as you describe, HAVE to put persitance code in your model layer. YIKES!

  • Black Jack Schule on on 6.29.2009 at 7:44 AM

    Black Jack Schule avatar

    I've been doing application development for decades (I won't mention how many) and have had to learn and use dozens of languages and development tools. In this time and place, I am a newbie, and I appreciate your efforts.

  • birmingham_escorts on on 8.18.2009 at 10:50 PM

    birmingham_escorts avatar

    I am trying to insert a new entity using LINQ-to-SQL, and entity is associated with a User entity. The insert of the new entity is successful, but my existing User entity gets inserted as if it were a new User.

  • http://www.promozionidelcasino.com/ on on 10.21.2009 at 11:53 PM

    http://www.promozionidelcasino.com/ avatar

    I really appreciate your work to this site.So continue this kind of stuff in future also.

  • ppo on on 1.05.2010 at 9:36 AM

    ppo avatar

    Hi Sara:

    I am looking for a php script that will grab data from a feed such as a feedburner feed and convert it into a post automatically. Any help

  • insurance on on 1.17.2010 at 7:36 AM

    insurance avatar

    I recently came across your blog and have been reading along. I thought I would leave my first comment. I love the way you write post!

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