ADO.NET team blog : LINQ to SQL

Update on LINQ to SQL and LINQ to Entities Roadmap

dpblogs — Thu, 30 Oct 2008 03:36:00 GMT

Since the release of LINQ to SQL and the Entity Framework, many questions have been raised about the future plans for the technologies and how they will relate to each other long term.
During this week of PDC we are now at a point, with the announcement of Visual Studio 10 and the .NET Framework 4.0, that we can provide more clarity on our direction.

We have seen great momentum with LINQ in the last year. In .NET Framework 3.5 we released several LINQ providers, including LINQ to SQL which set the bar for a great programming model with LINQ over relational databases. In .NET 3.5 SP1, we followed up that investment with the Entity Framework enabling developers to build more advanced scenarios and to use LINQ against any database including SQL Server, Oracle, DB2, MySQL, etc.

We’re making significant investments in the Entity Framework such that as of .NET 4.0 the Entity Framework will be our recommended data access solution for LINQ to relational scenarios. We are listening to customers regarding LINQ to SQL and will continue to evolve the product based on feedback we receive from the community as well.

Tim Mallalieu
Program Manager, LINQ to SQL and Entity Framework

Migrating from LINQ to SQL to Entity Framework: Deferred Loading

dpblogs — Thu, 16 Oct 2008 20:52:00 GMT

Last week, we covered Eager Loading and how to migrate LINQ to SQL based code that took advantage of Eager Loading. This week, we discuss Deferred Loading.

Generally speaking, queries only retrieve the objects you request, and not their related objects. Deferred Loading (or Lazy Loading) allows you to automatically load objects on demand if and when you attempt to access the object that is not yet loaded (you might do this by trying to access a property that allows you to get to the object you are interested in, for instance).

Automatic Deferred Loading has its advantages and disadvantages – automatic deferred loading that is on by default means more productivity and less code to write. However, it also means less control over when and how you hit the database. In LINQ to SQL, Automatic Deferred Loading is enabled by default, but it can be disabled by using the following code fragment. For more information, see Deferred versus Immediate Loading (LINQ to SQL).

db.DeferredLoadingEnabled = false;

In the example below, you are really only querying for objects from the Products table – however, because Deferred Loading is enabled, you can access prod.SalesOrderDetail (which automatically fetches the associated SalesOrderDetail values from the database, and surfaces the results as SalesOrderDetail objects for the particular product)

var products = from prod in db.Products
               where prod.Color == "Blue"
               select prod;

foreach (Product prod in products)
{
    foreach (SalesOrderDetail detail in prod.SalesOrderDetail)
    {
        // do something with detail
    }
}

The Entity Framework does not provide an automatic mechanism for deferred loading. However, a simple addition to the code above achieves the same result.

var products = from prod in db.Product
               where prod.Color == "Blue"
               select prod;

foreach (Product prod in products)
{
    // avoids unnecessary queries
    if (!prod.SalesOrderDetail.IsLoaded)
    {
        prod.SalesOrderDetail.Load();
    }

    foreach (SalesOrderDetail detail in prod.SalesOrderDetail)
    {
        // do something with detail
    }
}

For more information, see Navigation Properties. Also see Jaroslaw Kowalski’s blog series Transparent Lazy Loading for Entity Framework which discusses the EFLazyClassGen samples available on CodeGallery. EFLazyClassGen could also be extended to support a Link<T> style deferred loading of individual properties.

In our next post, we will look at Stored Procedures. Stay tuned and let us know what you think!

- The ADO.NET Team

Connecting to Pre-Release Versions of SQL Server 2008 – Part Deux

dpblogs — Mon, 07 Apr 2008 21:24:00 GMT

Since posting on the topic of design-time and runtime connectivity to pre-release versions of SQL Server 2008 on the Data blog in November, the set of affected clients (applications, runtimes, and operating systems) have been officially released: Microsoft Visual Studio 2008, Microsoft .NET Framework v3.5, Microsoft Vista Service Pack 1, and Microsoft Windows 2008. Runtime connectivity from a client system configured with any of these released products to SQL Server 2008 November CTP or later provides full runtime access to the following features (for design-time functionality, see below):

· Table-Valued Parameters

· New date/time data types

· Large user-defined types

· Support for very large FILESTREAM-attributed column data

Design-Time Connectivity Between Visual Studio and SQL Server 2008

Developers using Visual Studio 2005 or Visual Studio 2008 design tools will receive an error when trying to open a database on any pre-release instance of SQL Server 2008 without installing a Visual Studio patch. Pre-release patches for Visual Studio 2008 and Visual Studio 2005 enable the following Visual Studio functionality for SQL Server 2008:

· Server Explorer successfully connects to SQL Server 2008, and database objects such as stored procedures and table data can be viewed and edited.

o Note that table schemas still cannot be viewed or edited in this release.

· SQL CLR projects that target SQL Server 2008 can be created and deployed to the server.

· T-SQL and SQL CLR debugging are now enabled for SQL Server 2008.

· Data binding features in Client and Web Projects are enabled.

Pre-release versions of the design-time patches are currently available: the Visual Studio 2008 CTP patch is available for download here and the Visual Studio 2005 CTP patch is available for download here. Final versions of the patches will be available in the near future. For more information please see the "Connecting to Microsoft SQL Server 2008 from Microsoft Visual Studio 2005 and 2008" whitepaper on MSDN.

Debra Dove

Program Manager Lead, Data Programmability

Coming soon to LINQ to SQL

dpblogs — Thu, 21 Feb 2008 22:28:00 GMT

LINQ to SQL went gold a few months ago with the release of Visual Studio 2008 and .NET Framework 3.5. It has been somewhat quiet since then – and as we near the launch of Visual Studio 2008, you may be wondering what we have been up to.

Things aren’t so quiet over here on our end, even if it looks that way. The team has been busy adding features so that you will have better support for SQL Server 2008 in the future. Things we’ve been working on include support for new T-SQL data types that are being introduced in SQL Server 2008 – namely DATE, TIME, DATETIME2 and DATETIMEOFFSET, so that you can enjoy the same rich LINQ support and CUD support over data that uses many of the new types that are being introduced in SQL Server 2008.

Watch this blog for more on this as we get closer to releasing some of this functionality!

Faisal Mohamood

Program Manager – LINQ to SQL

New ADO.NET Team Members - Part 2

dpblogs — Wed, 05 Dec 2007 02:18:00 GMT

Hi – I’m Faisal Mohamood and I’m a Program Manager for LINQ to SQL and Object Services for Entity Framework. I’m a fairly recent addition to the team, and prior to this I was Program Manager on the Visual Studio Platform team, looking after parts of MSBuild and the Visual Studio platform.

I see lots of opportunities to revolutionize the way we think about data and the way we go about supercharging data access - so I’m excited to be a part of this team. I look forward to engaging with you and having conversations with you via blogs as forums – so you’ll certainly be seeing more from me about the Entity Framework, LINQ to SQL, and other cool technologies we are working on.

Faisal Mohamood

Program Manager, ADO.NET