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LINQ to SQL vs. ADO.NET Entity Framework RRS feed

  • Question

  • I know this has been asked before, but the answers I've read still haven't cleared it up for me. People are asking me why they should wait around for an updated to ADO.NET Entity Framework (not currently linked to the Orcas builds) or if they should use LINQ to SQL, which _is_ part of Orcas.

    Can someone clarify, hopefully in a way that can be repeated to others, what exactly the benefit of LINQ to SQL is over the EF and the other way around? I am hoping that there is little overlap between the purposes of these solutions and that there is a clear list of situations in which it makes more sense to use one over the other.
    Friday, July 27, 2007 10:48 AM

Answers

  • Kevin;

     

    LINQ to SQL and the Entity Framework have a lot in common, but each have features targeting different scenarios in the Orcas timeframe.

     

    LINQ to SQL has features targeting "Rapid Development" against a Microsoft SQL Server database. Think of LINQ to SQL as allowing you to have a strongly-typed view of your existing database schema. LINQ to SQL supports a direct, 1:1 mapping of your existing database schema to classes; a single table can be mapped to a single inheritance hierarchy (i.e., a table can contain persons, customers, and employees) and foreign keys can be exposed as strongly-typed relationships.  You can build LINQ queries over tables/views/table valued functions and return results as strongly typed objects, and call stored procedures that return strongly typed results through strongly typed methods.  A key design principle of LINQ to SQL is that it "just work" for the common cases; so, for example, if you access a collection of orders through the Orders property of a customer, and that customer's orders have not previously been retrieved, LINQ to SQL will automatically get them for you.  LINQ to SQL relies on convention, for example default insert, update, and delete logic through generated DML can be overwritten by exposing appropriately named methods (for example, "InsertCustomer", "UpdateCustomer", "DeleteCustomer").  These methods may invoke stored procedures or perform other logic in order to process changes.

     

    The Entity Framework has features targeting "Enterprise Scenarios".  In an enterprise, the database is typically controlled by a DBA, the schema is generally optimized for storage considerations (performance, consistency, partitioning) rather than exposing a good application model, and may change over time as usage data and usage patterns evolve.  With this in mind, the Entity Framework is designed around exposing an application-oriented data model that is loosely coupled, and may differ significantly, from your existing database schema.  For example, you can map a single class (or "entity") to multiple tables/views, or map multiple classes to the same table/view. You can map an inheritance hierarchy to a single table/view (as in LINQ to SQL) or to multiple tables/views (for example, persons, customers, and employees could each be separate tables, where customers and employees contain only the additional columns not present in persons, or repeat the columns from the persons table).  You can group properties into complex (or “composite”) types (for example, a Customer type may have an “Address” property that is an Address type with Street, City, Region, Country and Postal code properties). The Entity Framework lets you optionally represent many:many relationships directly, without representing the join table as an entity in your data model, and has a new feature called "Defining Query" that lets you expose any native query against the store as a "table" that can be mapped just as any other table (except that updates must be performed through stored procedures).  This flexible mapping, including the option to use stored procedures to process changes, is specified declaratively in order to account for the schema of the database evolving over time without having to recompile the application.

     

    The Entity Framework includes LINQ to Entities which exposes many of the same features as LINQ to SQL over your conceptual application data model; you can build queries in LINQ (or in “Entity SQL”, a canonical version of SQL extended to support concepts like strong typing, polymorphism, relationship navigation and complex types), return results as strongly typed CLR objects, execute stored procedures or table valued functions through strongly-typed methods, and process changes by calling a single save method.

     

    However, the Entity Framework is more than LINQ to Entities; it includes a "storage layer" that lets you use the same conceptual application model through low-level ADO.NET Data Provider interfaces using Entity SQL, and efficiently stream results as possibly hierarchical/polymorphic DataReaders, saving the overhead of materializing objects for read-only scenarios where there is no additional business logic. 


    The Entity Framework works with Microsoft SQL Server and 3rd party databases through extended ADO.NET Data Providers, providing a common query language against different relational databases through either LINQ to Entities or Entity SQL.

     

    So while there is a lot of overlap, LINQ to SQL is targeted more toward rapidly developing applications against your existing Microsoft SQL Server schema, while the Entity Framework provides object- and storage-layer access to Microsoft SQL Server and 3rd party databases through a loosely coupled, flexible mapping to existing relational schema.

     

    I know this is a confusing area, and we’re trying to figure out how best to describe these differences to help customers make the appropriate choices.  Please let me know if this helps, or if there are still areas of confusion…


    Thanks,

     

    Michael Pizzo

    Principal Architect

    Microsoft Data Programmability

    Monday, July 30, 2007 6:26 PM

All replies

  • Kevin,

     

    Have you read the post on Microsoft's data access strategy that talks about the differences between LINQ to SQL and LINQ to Entities?  Does this make it clearer to you or are you looking for something else? 

     

    -Lance

    Saturday, July 28, 2007 4:42 PM
  • Kevin;

     

    LINQ to SQL and the Entity Framework have a lot in common, but each have features targeting different scenarios in the Orcas timeframe.

     

    LINQ to SQL has features targeting "Rapid Development" against a Microsoft SQL Server database. Think of LINQ to SQL as allowing you to have a strongly-typed view of your existing database schema. LINQ to SQL supports a direct, 1:1 mapping of your existing database schema to classes; a single table can be mapped to a single inheritance hierarchy (i.e., a table can contain persons, customers, and employees) and foreign keys can be exposed as strongly-typed relationships.  You can build LINQ queries over tables/views/table valued functions and return results as strongly typed objects, and call stored procedures that return strongly typed results through strongly typed methods.  A key design principle of LINQ to SQL is that it "just work" for the common cases; so, for example, if you access a collection of orders through the Orders property of a customer, and that customer's orders have not previously been retrieved, LINQ to SQL will automatically get them for you.  LINQ to SQL relies on convention, for example default insert, update, and delete logic through generated DML can be overwritten by exposing appropriately named methods (for example, "InsertCustomer", "UpdateCustomer", "DeleteCustomer").  These methods may invoke stored procedures or perform other logic in order to process changes.

     

    The Entity Framework has features targeting "Enterprise Scenarios".  In an enterprise, the database is typically controlled by a DBA, the schema is generally optimized for storage considerations (performance, consistency, partitioning) rather than exposing a good application model, and may change over time as usage data and usage patterns evolve.  With this in mind, the Entity Framework is designed around exposing an application-oriented data model that is loosely coupled, and may differ significantly, from your existing database schema.  For example, you can map a single class (or "entity") to multiple tables/views, or map multiple classes to the same table/view. You can map an inheritance hierarchy to a single table/view (as in LINQ to SQL) or to multiple tables/views (for example, persons, customers, and employees could each be separate tables, where customers and employees contain only the additional columns not present in persons, or repeat the columns from the persons table).  You can group properties into complex (or “composite”) types (for example, a Customer type may have an “Address” property that is an Address type with Street, City, Region, Country and Postal code properties). The Entity Framework lets you optionally represent many:many relationships directly, without representing the join table as an entity in your data model, and has a new feature called "Defining Query" that lets you expose any native query against the store as a "table" that can be mapped just as any other table (except that updates must be performed through stored procedures).  This flexible mapping, including the option to use stored procedures to process changes, is specified declaratively in order to account for the schema of the database evolving over time without having to recompile the application.

     

    The Entity Framework includes LINQ to Entities which exposes many of the same features as LINQ to SQL over your conceptual application data model; you can build queries in LINQ (or in “Entity SQL”, a canonical version of SQL extended to support concepts like strong typing, polymorphism, relationship navigation and complex types), return results as strongly typed CLR objects, execute stored procedures or table valued functions through strongly-typed methods, and process changes by calling a single save method.

     

    However, the Entity Framework is more than LINQ to Entities; it includes a "storage layer" that lets you use the same conceptual application model through low-level ADO.NET Data Provider interfaces using Entity SQL, and efficiently stream results as possibly hierarchical/polymorphic DataReaders, saving the overhead of materializing objects for read-only scenarios where there is no additional business logic. 


    The Entity Framework works with Microsoft SQL Server and 3rd party databases through extended ADO.NET Data Providers, providing a common query language against different relational databases through either LINQ to Entities or Entity SQL.

     

    So while there is a lot of overlap, LINQ to SQL is targeted more toward rapidly developing applications against your existing Microsoft SQL Server schema, while the Entity Framework provides object- and storage-layer access to Microsoft SQL Server and 3rd party databases through a loosely coupled, flexible mapping to existing relational schema.

     

    I know this is a confusing area, and we’re trying to figure out how best to describe these differences to help customers make the appropriate choices.  Please let me know if this helps, or if there are still areas of confusion…


    Thanks,

     

    Michael Pizzo

    Principal Architect

    Microsoft Data Programmability

    Monday, July 30, 2007 6:26 PM
  • The best description so far of the differences between Linq and EF. 

    ChrisB
    Thursday, August 23, 2007 7:40 AM
  • Thanks Michael.

     

    Where does Jasper come into picture? How Jasper and “LINQ to Entities” are related?

     

    Monday, September 24, 2007 2:19 PM
  • The first thing you need to know is that Jasper is an incubation effort--that is to say, it is a project where we did some exploration and wanted to get it out to the public to look at and provide some feedback and thinking about.  At some point it or something like it might become a product, but there isn't currently a concrete plan to do so in any particular timeframe.

     

    That said, Jasper is built on top of the entity framework (aka linq to entities).  Basically it's an even higher abstraction designed to show how dynamic languages, the entity framework and concepts like configuration by convention might work together.

     

    - Danny

     

    Tuesday, September 25, 2007 4:14 AM
  • Thanks Danny.

     

    Tuesday, September 25, 2007 4:44 AM
  • I have some questions about LINQ to SQL vs ADO Entities.

     

    We are doing Silverlight 2 applications leveraging the LINQ to SQL objects via WCF web services. This allows us to enable the Unidirectional serializing features of LINQ to SQL objects to transport our objects over WCF to SL2 applications.

     

    Although we are hitting some problems.
    1. We get circular reference exceptions during serialization if we don't remove either the Child or Parent property.

    2. Many to many isn't handled very well.

     

    As for #1, We would ideally want both ends of the relationship serialized but for the serializer to somehow be smart enough to not go into circles. Although we can disable one of the properties end points, there are cases when we are querying and require either end so 1 setup does not fit all.

     

    Does ADO Entities deal with this situation better than LINQ to SQL? The problem as I understand it in LINQ to SQL is its trying to serialize something like:

     

    Order.OrderItems[0].Order.OrderItems[0].Order etc...

     

    Because both sides of the table relations create properties to get to the other side on both ends the serializer hits a circular reference.

     

    Although it would be ideal to still maintain both ends but have the serializer not go into this loop after depth of 1 type thing.

     

    Any feedback would be greatly appreciated!

     

    Monday, May 12, 2008 5:16 PM
  • With VS 2008 SP1 beta which was released this morning you will find changes both to the EF and to WCF which make it possible to remote graphs of entities transparently.  This will work for 1-1, 1-many and many-many relationships, and the changes to EF & WCF deal with circular references automatically.  I haven't yet done tests on combining this with silverlight 2, however.  Should be fine, but I won't claim anything when I haven't tried it yet.

     

    - Danny

     

    Monday, May 12, 2008 7:15 PM
  • Great!

     

    Do you know if this is a Entities fix or a WCF serialization in general fix? I have already started teaching some LINQ to SQL so it would be great if circular serialization can be avoided there as well from which I can start teaching Entities after.

    Monday, May 12, 2008 7:19 PM
  • It was a fix that required changes on both sides.  I do not believe LINQ to SQL will benefit from this without some changes there that haven't been made.

     

    - Danny

     

    Monday, May 12, 2008 10:06 PM
  • Ah. That is very unfortunate. I am having a real hard time finding LINQ to SQL useful without this. I am hitting tons of relations where I require both ends of the relation.

     

    Also an issue I am having trouble getting any clarity on is I need WCF to serialize data based on ASP.NET roles.

     

    Is there any way in ADO.NET Entities I can sublcass from the serializer so that I can check attributes applied to fields (partial classes perhaps with attributes defined on fields?) and not serialize certain fields?

     

    Reason being is sometimes the user does not have permission to even receive certain fields and enforcing this on the client-side is a security concern as you can understand. Very rarely do we want an entire table to serialize. Although sometimes with higher roles you may want more fields serialized than lower roles.

     

    Any help with this would be GREATLY appreciated.

     

    Thanks and take care.

     

    Monday, May 12, 2008 10:42 PM
  • The entity framework doesn't contain any facility to support that kind of scenario out of the box--it's really more of a WCF / DataContract concern.  It might be that Data Contract Surrogates would help, but I'm not certain.

     

    - Danny

    Tuesday, May 13, 2008 6:04 AM
  • Who can I talk to about this? I've pinged the SL forum, some people who have blogs, the WCF forum, the LINQ forum I just don't know where to ask this question any longer.

     

    Surrogates are not supported in Silverlight 2. There has got to be a way to enforce security on our data object model outside of writting proxy classes for each object which defeats the whole idea of these O/R classes having serialization support.

     

    I'm not feeling its acceptable to serialize sensative information over the wire and use the client-side to enforce security of the data.

     

    Any help would be greatly appreciated.

    Wednesday, May 14, 2008 5:13 PM
  • I agree that this is an important scenario.  Unfortunately I don't have a super-simple solution for you in the current versions of the product.  There are some options that you can look at:

     

    1) You could, as you mention, write separate classes that represent your data contract and not directly serialize entities to the client.  If you did this, you could either write them by hand or you could use a code generator to do it.  One nice thing about this approach is that it allows you to have a stronger abstraction boundary with your client which could be nice if you someday want to change the mid-tier schema/object model without changing your client code, but of course it is a fairly big hammer to add an entire additional layer to your system.

    2) You could move the data that needs to be kept from the client into separate entities so that it's easy to have access to both entities on the mid-tier but only one entity on the client.  This has unpleasant side-effects on your modeling, though, and may even require database changes.

     

    3) You could create your own entity classes directly instead of using our code generator (or use your own code generator).  When you do that you could choose which properties to make data members and which not to.

     

    In future releases of the Entity Framework we'll work on several strategies that might help here including easier ways to customize codegen, etc.

     

    - Danny

     

    Saturday, May 17, 2008 8:39 PM
  • For what it's worth, our friends at IdeaBlade have take approach #1, which has allowed them to do some fairly cool things:

    http://www.ideablade.com/DevForceEF_summary.html

    Saturday, May 17, 2008 10:00 PM
  • Entity Framework is recommended by MS for Enterprise scenarios, but it was pathetic to find that it the current release has got (v 1) has got deadly short comings that make it seriously crippled.
    Here are some of the practical issues we faced.
    http://geekswithblogs.net/SudheersBlog/archive/2009/06/03/132600.aspx

    Thursday, June 4, 2009 12:48 PM
  • Interesting blog post, Sudheer. Between what you point out and issues with inferred keys from views I think I will steer clear of EF for the foreseeable future.
    Friday, October 2, 2009 7:31 PM
  • So here it is many years later from these original posts.  What's current state of EntityFramework?  Anyone know?
    Javaman
    Wednesday, January 12, 2011 11:35 PM
  • The EF4 is much stronger than it was in .NET 3.5.  Everything from testability (though the addition of interface IObjectSet<T>), usability (via edmx designer improvements), to the utilization/creation of complex types, to how much easier it is to use stored procedures.  Personally, I love EF4.
    Wednesday, January 12, 2011 11:55 PM
  • The EF4.1 came packed with two additional features which is having a great potential which are worth a try

    1. DBContext API
    2. Code First

    There is a great article there by "Rowan Miller"

    http://blogs.msdn.com/b/adonet/archive/2011/03/15/ef-4-1-code-first-walkthrough.aspx

    Tuesday, July 5, 2011 2:13 PM
  • Hi,

    We are using .net 3.5, we are processing a file that contains french descriptions

    that needs to be get inserted ito the sql server,

     

    we use the entity classes with linq to sql which inserts the data on the fly in to the sqlserver, however, after insertion, we find some french characters are not properly

    inserted into the specific table of the database.

     

    When we tried to insert the french descriptions manually into the db, it get inserted,

    Any help would be appreciated.

     

    Thanks alot.

    G.

    Monday, October 31, 2011 7:09 PM
  • Any help on the above please.

     

    Thanks.

    G

    Monday, October 31, 2011 9:28 PM