I got confused on what are the differences between Linq-to-SQL and Entity Framework when following the database first approach as I can not find any clear differences.
In my case when I was using Linq-to-SQL I used to create the tables then I use Linq-to-SQL to create the classes that represents the tables, and now when I switch to Entity Framework I am still following the same steps (creating the database tables then create the associated classes using EF).
And I am interacting with these classes on the same way, for example I used to query the User class using the same syntax and approach but one time when the User class was created using Linq-to-SQL and the other time when it was created using EF, so where is the difference ?
public IQueryable<User> findstudents(string term)
{
return from student in entities1.Users
where student.UserID.Contains(term)
select student;
}
Second question if I use EF to map the tables into classes, is it still possible to use Linq-to-SQL in the same application to query the EF classes?
LINQ is a base technology - that's the syntax that gives you the SQLish query options in C# - that's totally independent of whether you use Linq-to-SQL or EF. So if you want to query your data classes using the LINQ syntax - you can do that with both frameworks - but once you use Linq-to-SQL and once you use Linq-to-Entities. You cannot use Linq-to-SQL against an Entity Framework EDMX model.
Linq-to-SQL is great
if you need very simple 1:1 mapping - one table equals one class in your domain model
if you never need anything else but SQL Server (Linq-to-SQL doesn't support anything else)
if you want to be up and running really quickly
Entity Framework on the other hand
supports multiple backends (SQL Server, Oracle, Firebird - other will likely follow)
supports a full conceptual data modelling strategy - you define the physical model in the database, the conceptual model in your app, and the mapping between the two
gives you the ability to handle things like mapping a single business entity to several tables
support table-per-hierarchy and table-per-class inheritance scenarios
support refreshing/updating your model (EDMX file) from the database when things change (in Linq-to-SQL, you basically have to drop + recreate those entities involved - thus loosing all your customizations you might have made)
In brief: Linq-to-SQL is a great, simple and lean'n'mean ORM for SQL Server - use it, if it does all you need. Entity Framework is quite a different beast, much more capable, but also more complex, much bigger - perfect for your next enterprise-critical app, but probably overkill for your personal blog app :-)
If you want to create something that's "future-proof" and will use the OR technology that Microsoft is pushing into the future, then you should go with Entity Framework. Especially in v4, it's also a lot easier to use, a lot more slimmed down and more useful than ever before.
Related
I had a conceptual question about EF.
I am pretty new to the idea of an ORM in general, so I wanted to get some clarification on somethings:
I have an existing database, and I want to convert the data I am pulling from that data into objects that my application can interact with as objects, rather than just data.
An ORM will accomplish that, correct?
In EF can I create methods specific to my objects? For instance, can I make it so my application can call something like employee.ViewDetails() Where employee is an object?
If so, is there a simple tutorial you could recommend?
Is EF portable between applications? Meaning, is it easy to build an EF structure and then port it to multiple applications?
I can just do that by referencing it from different solutions, no?
Thanks for all the help
Before Answering your Question let me give you short brief about Entity Framework
Using the Entity Framework to write data-oriented applications provides the following benefits:
Reduced development time: the framework provides the core data access capabilities so developers can concentrate on application logic.
Developers can work in terms of a more application-centric object model, including types with inheritance, complex members, and relationships. In .NET Framework 4, the Entity Framework also supports Persistence Ignorance through Plain Old CLR Objects (POCO) entities.
Applications are freed from hard-coded dependencies on a particular data engine or storage schema by supporting a conceptual model that is independent of the physical/storage model.
Mappings between the object model and the storage-specific schema can change without changing the application code.
Language-Integrated Query support (called LINQ to Entities) provides IntelliSense and compile-time syntax validation for writing queries against a conceptual model.
Going Back to your first Question
Yes
Entity framework is useful in three scenarios.
1- First, if you already have existing database or you want to design your database ahead of other parts of the application. (Which is your current case)
2- Second, you want to focus on your domain classes and then create the database from your domain classes.
3- Third, you want to design your database schema on the visual designer and then create the database and classes.
2) in EF can I create methods specific to my objects? For instance, can I make it so my application can call something like employee.ViewDetails() where an employee is an object? If so, is there a simple tutorial you could recommend?
Yes Sure Take a look on this:
- https://msdn.microsoft.com/en-us/library/dd456847.aspx
- http://www.asp.net/mvc/overview/older-versions-1/models-data/creating-model-classes-with-the-entity-framework-cs
3) Is EF portable between applications? Meaning, is it easy to build an EF structure and then port it to multiple applications? I can just do that by referencing it from different solutions?
you might need to Implementing the Repository Patterns
Have a look at this Amazing tutorial
http://blog.gauffin.org/2013/01/repository-pattern-done-right/
http://rycole.com/2014/01/25/entity-framework-repository-pattern.html
Hope this helps!
Wish you the best :)
Blubberbo,
There are various ways to work with EF, they are Code First, Model First and Database first.
More information can be found in the below SO post.
Code-first vs Model/Database-first
1) You can use LINQ to SQL or LINQ Objects in context with an ORM like EF to interact with Objects.
2) If you would like methods specific to specific types, then you might want to take a look at writing extension methods for specific types.
More information here
https://msdn.microsoft.com/en-us/library/bb311042.aspx
3) To make it portable, you might want to build abstractions around it, like for example you might want to write repository classes to separate the DB layer that uses EF and the layer that calls it(a.k.a the repository layer).
More info can be found here
http://www.asp.net/mvc/overview/older-versions/getting-started-with-ef-5-using-mvc-4/implementing-the-repository-and-unit-of-work-patterns-in-an-asp-net-mvc-application
Hope that helps,
Praveen Raju
I have various objects that I would like to track in an application. The objects are computers, cameras, switches, routers etc. I want the various objects to inherit from an object called Device since they will all have some properties in common (i.e. IP Address, MAC Address, etc.) I like to create the objects using the designer (Model First) but I do not like the difficulty in updating the database from the model. Basically, I do not like to have to drop the database and recreate it, especially once I start populating the database. The other approach that I experimented with was creating the database using SSMS in SQL Server, but then when I create the POCOs from the database the entities do not inherit from each other. What is a good approach for my situation ?
I want the various objects to inherit from an object called Device since they will all have some properties in common (i.e. IP Address, MAC Address, etc.)
You are essentially talking about which inheritance pattern you are going to use in EF; or how the model maps to your database tables. There are 3 main types of inheritance patterns in EF (see Inheritance Mapping: A Walkthrough Guide for Beginners):
Table-per-Hierarchy
Table-per-Type
Table-per-Concrete Type
Each has pros and cons (such as performance). But, you should also consider that this model is a model that relates to the database, and in larger projects you might then create a second layer to work with for business logic. DDD talks about persistence models and domain models. Again, your choices here are weighing up initial speed of development and scalability and performance later on.
I like to create the objects using the designer (Model First) but I do not like the difficulty in updating the database from the model.
There are 4, and only 4 development strategies for EF (see Entity Framework Development Workflows):
Model First
Code First (new database)
Database First
Code-first (existing database)
I do not like to have to drop the database and recreate it, especially once I start populating the database
Code First is really very, very good at this:
Seeding in Code First allows you to populate databases with test or live data depending on where you are deploying to.
Migrations allow you to do non-destructive updates to the database, and migrate data in a fully testable, utterly reliable fashion for live deployment.
Doing this with Model First is, unfortunately, just harder. The only real solution I know is to generate a new database, and use a SQL compare (with data compare) tool to generate the data in the new database.
Choosing a pattern and a strategy
Each strategy has pros and cons, and each inheritance pattern is better used with particular development strategies. The trade offs are really your own to judge, for example you might have to use database-first if you have en existing database you inherited, or you may be happier using the EF designer so would use model-first.
Model First (by that I mean using the EF designer to define your model) uses the TPT strategy by default. See EF Designer TPT Inheritance. If you want TPH, then you can use Model-first (see EF Designer TPH Inheritance), but you have extra work to do; Code First is a better fit for TPH. TPC is even harder using Model First, and Code First is really the best (only viable) option for that in EF 5.
when I create the POCOs from the database the entities do not inherit from each other
It is good to remember that the model deals with classes; the database deals with storage in tables. When generating a model from your database it is hard for EF to work out what the TPH or TPC inheritance should be. All it can do is create a "best guess" at your model based on the table assocations. You have to help it out after the model is generated by renaming properties, changing associations or applying inheritance. There really is no other way to do this. Updates to the database may also therefore require more work on the model.
Your best approach
That is, unfortunately, down to opinion. However if your primary requirements are:
You want TPH or TPC (or mixed strategies)
You don't want to drop your database when you issue updates to the model
then the best match for these technical requirements is Code First development, with migrations and seeding.
The downside of Code First is having to write your own POCOs, and learning the data annotation attributes. However, keep in mind:
writing POCOs is not so different from writing a database table (and once you are used to it is is just as quick)
Code First is a lot more usable with automated testing (e.g. with DI and/or IoC to test without the database involved), so can have benefits later on
If you are going to do a lot of EDMX manipulation with database first, or a lot of work whenever you drop and update your database using model first, then you are just putting in time and effort in other places instead of in writing POCOs
I know the benefit of the LINQ and I know use of it in .Net Application. I fill same thing there are providing as a Entity Framework.
So What's Major Difference between LINQ and Entity Framework?
LINQ could be applied to any data source: in-memory objects, XML, SQL, ...
Entity Framework could use LINQ to perform queries against a relational database.
LINQ to SQL is the predecessor of Entity Framework and is obsolete now.
Comparing EF and LINQ is incorrect. Both are different things and they often work together to give better developer experience (and productivity benefit).
LINQ is querying syntax/model that can be applied to any data source. EF provides one such data source.
They are somewhat similar, and can be used in a very similar way, code-wise, but they have some important differences. Note that "LINQ" is not the same thing as "LINQ to SQL"; the EF also uses LINQ. Some notable differences are:
LINQ to SQL is largely SQL Server only, not so much by design as by implementation. The EF is designed to support, and does support, multiple DBs, if you have a compatible ADO.NET provider.
Out of the box, LINQ to SQL has a very poor story for DB metadata changes. You have to regenerate parts of your model from scratch, and you lose customizations.
The EF supports model features like many-to-many relationships and inheritance. LINQ to SQL does not directly support these.
In .NET 3.5, LINQ to SQL had much better support for SQL-Server-specific functionality than the EF. This is mostly not true in .NET 4; they're fairly similar in that respect.
The EF lets you choose Model First, DB First, or Code First modeling. LINQ to SQL, out of the box, really only supports DB First.
SOURCE : Here
I totally agree with VinayC. You cannot really compare.
With Entity Framework, you will be able to have a whole representation of your database in your program. It will help you create classes corresponding to the database elements, connected together like they are in the database. You can after interact with elements of theses classes directly, and like this impact the database. You will have some representation of these classes diagram in visual studio. It's basically often simpler than working directly with the database elements, even if setting it up requires some effort.
The use of Linq is to perform queries on the data sources.
I am working on window application developed using SCSF and we are using sybase database. As practise we create typedataset in the .net project and then populate them using framework method and for all the sql statement we write stored procedure in the database.
So we have type dataset in memory so I am using linq to select records from datatable. Can I step one step further and use something related to Entity Framework?
Can it reduce my work? I don't have hands-on experience with Entity Framework but can you suggest something in this scenario?
Thanks,
Denish
Entity framework uses similar concepts as the type datasets except for:
The ability to have a class structure that is not exactly the same as the table structure (e.g. class hierarchy, splitting tables into multiple classes, joining tables into one class).
The ability to use LINQ to perform queries in the database instead of in memory.
Entity framework also lets you map results of stored procedures to classes and bring results into memory if you need to run a query that is faster in memory or not translatable to SQL.
For most SQL queries the LINQ to Entity will be effective enough, so you will probably end up writing less stored procedures.
You will have to learn how to use EF and LINQ effectively and use can use 3rd party tools such as Entity Framework Profiler to help you.
I know the high-level differences between linq to sql and entity framework, however, I am hoping for advice from someone else who has already made the switch themselves, or has sufficient experience with both. Coming from a strong linq to sql background, as far as implementation and low-level details, are there any important things I need to know as I start coding my new data access layer project with entity framework?
I already created my edmx file (I chose the database-first approach), and everything just seems suspiciously identical to linq to sql so far. What would help me is a short list of items, like, in linq to sql, you do [this] [this way], but in entity framework, you'll want to do it [this way].
Sorry if this is a strange question, but any attempts at answers would be greatly appreciated. Thanks!
In new project between L2S and EF I suggest EF (consider Entity Framework version 4.0 or superior, DON'T use early EF releases).
While Linq to SQL is a class to table mapping EF 4 is a complete ORM (Object Relational Mapping) tool with different mapping scenarios.
With EF you have a lot of flexibility:
Database First approach
Model First approach
Code First approach
and a strong integration with LINQ Provider.
Unit testing with Linq2SQL is a nightmare.
With EF you have POCO (Plain Old CLR Object) classes out of the box. In L2S the entity class is tight coupled to the L2S namespace.
EF can help you also in Domain Driven Design scenarios.
Microsoft consider now EF the first database access method and it's the base for other services like RIA services or MVC database scaffolding.
LinqToSql is now the first database access methodology only in Windows Phone scenarios.
NH is far better... but again as EF is microsoft baby, it will grow as time goe