.net - with - Entity Framework vs LINQ to SQL




linq to sql vs linq to entities (11)

Now that .NET v3.5 SP1 has been released (along with VS2008 SP1), we now have access to the .NET entity framework.

My question is this. When trying to decide between using the Entity Framework and LINQ to SQL as an ORM, what's the difference?

The way I understand it, the Entity Framework (when used with LINQ to Entities) is a 'big brother' to LINQ to SQL? If this is the case - what advantages does it have? What can it do that LINQ to SQL can't do on its own?


Linq-to-SQL

It is provider it supports SQL Server only. It's a mapping technology to map SQL Server database tables to .NET objects. Is Microsoft's first attempt at an ORM - Object-Relational Mapper.

Linq-to-Entities

Is the same idea, but using Entity Framework in the background, as the ORM - again from Microsoft, It supporting multiple database main advantage of entity framework is developer can work on any database no need to learn syntax to perform any operation on different different databases

According to my personal experience Ef is better (if you have no idea about SQL) performance in LINQ is little bit faster as compare to EF reason LINQ language written in lambda.


LINQ to SQL

  1. Homogeneous datasource: SQL Server
  2. Recommended for small projects only where data structure is well designed
  3. Mapping can be changed without recompilling with SqlMetal.exe
  4. .dbml (Database Markup Language)
  5. One-to-one mapping between tables and classes
  6. Supports TPH inheritance
  7. Doesn't support complex types
  8. Storage-first approach
  9. Database-centric view of a database
  10. Created by C# team
  11. Supported but not further improvements intended

Entity Framework

  1. Heterogeneus datasource: Support many data providers
  2. Recommended for all new projects except:
    • small ones (LINQ to SQL)
    • when data source is a flat file (ADO.NET)
  3. Mapping can be changed without recompilling when setting model and mapping files Metadata Artifact Process to Copy To Output Directory
  4. .edmx (Entity Data Model) which contains:
    • SSDL (Storage Schema Definition Language)
    • CSDL (Conceptual Schema Definition Language)
    • MSL (Mapping Specification Language)
  5. One-to-one, one-to-many, many-to-one mappings between tables and classes
  6. Supports inheritence:
    • TPH (Table Per Hierarchy)
    • TPT (Table Per Type)
    • TPC (Table Per Concrete Class)
  7. Supports complex types
  8. Code-first, Model-first, Storage-first approaches
  9. Application-centric view of a database
  10. Created by SQL Server team
  11. Future of Microsoft Data APIs

See also:


I found a very good answer here which explains when to use what in simple words:

The basic rule of thumb for which framework to use is how to plan on editing your data in your presentation layer.

  • Linq-To-Sql - use this framework if you plan on editing a one-to-one relationship of your data in your presentation layer. Meaning you don't plan on combining data from more than one table in any one view or page.

  • Entity Framework - use this framework if you plan on combining data from more than one table in your view or page. To make this clearer, the above terms are specific to data that will be manipulated in your view or page, not just displayed. This is important to understand.

With the Entity Framework you are able to "merge" tabled data together to present to the presentation layer in an editable form, and then when that form is submitted, EF will know how to update ALL the data from the various tables.

There are probably more accurate reasons to choose EF over L2S, but this would probably be the easiest one to understand. L2S does not have the capability to merge data for view presentation.


I found that I couldn't use multiple databases within the same database model when using EF. But in linq2sql I could just by prefixing the schema names with database names.

This was one of the reasons I originally began working with linq2sql. I do not know if EF has yet allowed this functionality, but I remember reading that it was intended for it not to allow this.


I think the quick and dirty answer is that

  • LINQ to SQL is the quick-and-easy way to do it. This means you will get going quicker, and deliver quicker if you are working on something smaller.
  • Entity Framework is the all-out, no-holds-barred way to do it. This means you will take more time up-front, develop slower, and have more flexibility if you are working on something larger.

If your database is straightforward and simple, LINQ to SQL will do. If you need logical/abstracted entities on top of your tables, then go for Entity Framework.


My experience with Entity Framework has been less than stellar. First, you have to inherit from the EF base classes, so say good bye to POCOs. Your design will have to be around the EF. With LinqtoSQL I could use my existing business objects. Additionally, there is no lazy loading, you have to implement that yourself. There are some work arounds out there to use POCOs and lazy loading, but they exist IMHO because EF isn't ready yet. I plan to come back to it after 4.0


My impression is that your database is pretty enourmous or very badly designed if Linq2Sql does not fit your needs. I have around 10 websites both larger and smaller all using Linq2Sql. I have looked and Entity framework many times but I cannot find a good reason for using it over Linq2Sql. That said I try to use my databases as model so I already have a 1 to 1 mapping between model and database.

At my current job we have a database with 200+ tables. An old database with lots of bad solutions so there I could see the benefit of Entity Framework over Linq2Sql but still I would prefer to redesign the database since the database is the engine of the application and if the database is badly designed and slow then my application will also be slow. Using Entity framework on such a database seems like a quickfix to disguise the bad model but it could never disguise the bad performance you get from such a database.


The answers here have covered many of the differences between Linq2Sql and EF, but there's a key point which has not been given much attention: Linq2Sql only supports SQL Server whereas EF has providers for the following RDBMS's:

Provided by Microsoft:

  • ADO.NET drivers for SQL Server, OBDC and OLE DB

Via third party providers:

  • MySQL
  • Oracle
  • DB2
  • VistaDB
  • SQLite
  • PostgreSQL
  • Informix
  • U2
  • Sybase
  • Synergex
  • Firebird
  • Npgsql

to name a few.

This makes EF a powerful programming abstraction over your relational data store, meaning developers have a consistent programming model to work with regardless of the underlying data store. This could be very useful in situations where you are developing a product that you want to ensure will interoperate with a wide range of common RDBMS's.

Another situation where that abstraction is useful is where you are part of a development team that works with a number of different customers, or different business units within an organisation, and you want to improve developer productivity by reducing the number of RDBMS's they have to become familiar with in order to support a range of different applications on top of different RDBMS's.


There are a number of obvious differences outlined in that article @lars posted, but short answer is:

  • L2S is tightly coupled - object property to specific field of database or more correctly object mapping to a specific database schema
  • L2S will only work with SQL Server (as far as I know)
  • EF allows mapping a single class to multiple tables
  • EF will handle M-M relationships
  • EF will have ability to target any ADO.NET data provider

The original premise was L2S is for Rapid Development, and EF for more "enterprisey" n-tier applications, but that is selling L2S a little short.






linq-to-sql