These are the first two. I’ve got more coming!

If you don’t have a Pluralsight subscription, grab a free guest pass and you’ll have have access since these are part of the subset of guest pass content along with a ton of other great videos.

These will also be on MSDN online shortly.

Perhaps the title of this blog post will suffice, but I just wanted to highlight this problem.

If you were to look up the timestamp data type in the SQL Server 2008 documentation, this is waht you will find within the topic article:

“The timestamp syntax is deprecated. This feature will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature.”

It’s been there for quite some time.

The functionality of rowversion and timestamp are the same. It’s just a name change to align with the rest of the world and end the confusion caused by the word “time” in the name.

So let’s say you are good at following these types of recommendations and as you create a new table in SQL Server Managmenet studio, you attempt to use rowversion rather than timestamp.

Here’s what you’ll see:

rowversion is not an option.

It’s also not an option if you try to use the column’s properties window.

You can use TSQL to create the column:

ALTER TABLE dbo.Address ADD RowVersion rowversion

But the designer will still display it as a timestamp. The object explorer also says its a timestamp.

What about Visual Studio 2010?

The server explorer doesn’t grok rowversion either and shows the field as a timestamp.

And finally, the tool I use frequently, the Entity Data Model designer also does not recognize rowversion.

If I create an entity from this table, the store schema’s representation of the field is:

<Property Name="RowVersion" Type="timestamp" Nullable="false" StoreGeneratedPattern="Computed" />

I can change this manually and it is valid within the schema.

I’m confused. Microsoft wants us to use rowversion but they sure don’t make it easy!

Again, timestamp and rowversion do exactly the same thing. This is only a “decorative” change.

Yet, I care a lot about this because I use timestamp fields in the sample database for my book, Programming Entity Framework. The term “timestamp” shows up in many screenshots and I discuss it frequently throughout the book. I am considering taking on the task of changing every visual and textual reference to rowversion to be in line with Microsoft’s recommendations. Bt if it’s not easy for users to use the rowversion type, I’m very hesitant to force it on them.

If like me, you have a “can’t live with it, can’t live without it” relationship with Crystal Reports and have made a significant investment in reporting with their tools, you might be digging around the VS2010 RC looking for Crystal.

CR has been embedded into Visual Basic and Visual Studio for many versions. My experience goes back as far as Visual Basic 4, but in fact it started in 1993 with VB 2!

But it’s not in VS2010 RC. Well, kinda not in there.

Crystal Report is included in the project item templates:

But when you select it, something odd happens. Rather than a designer, you will get this window:

So it’s still available as a free extension to VS, just not built in. It’s odd that Crystal isn’t listed in the Extensions gallery that you can access through the VS2010 Extension Manager (on the Tools menu) or online at www.visualstudiogallery.com.

There’s an extensive blog post on the SAP website about Crystal Reports for Visual Studio 2010 which also lists new features, including a WPF report viewer.

I haven’t tried any of them out yet. What I’m most interested in is the design time experience with Entity Framework graphs. In VS2008, neither CR nor MS Reports recognizes navigation properties. A quick look at MS Reports (rdlc) in VS2010 suggests that this hasn’t changed. I’ll have to dig further at some point.

Remember… the data service is an item template, not a project template….and that it’s been renamed to WCF Data Services.

After you create a project (I usually use an empty web app to host the service), you can find the template in the Web section.

Or just use the handy search feature in the items dialog

Hooray! Turns out it was a bug ("unintended breaking change) and it’s getting fixed for RTM! 🙂 [see Connect submission and Microsoft’s response] Great catch George!

This is an edge case that I had not noticed, but was brought to my attention this morning in an email from Dave Russell who pointed me to this forum thread: EF4 Include method returns different results than EF1 Include

I had to test it myself because that’s the way I am.

Here is a model with the same set up : a many-to-many relationship between Person & Brewery defined using a join entity (FavoriteBrewery) and Brewery has a one-to-many relationship with Beer.

Putting a Stake in the Ground with .NET 3.5

This is the .NET 3.5 version of the model with no foreign keys.

If I query for all people

var list = context.People.ToList();

I get back 137 people.

If I query for all people who have any FavoriteBreweries:

list = context.People.Where(p => p.FavoriteBreweries.Any()).ToList();

I see there are only 3 people who have favorite breweries

Now let’s start eager loading.

list = context.People.Include("FavoriteBreweries").ToList();

This gives me all 137 people, with those favorite breweries attached to 3 of the people. (I checked by querying the ObjectStateManager for entries that are FavoriteBrewery types.)

Next, I eager load the Brewery objects along with those FavoriteBrewery join entities.

list = context.People.Include("FavoriteBreweries.Brewery").ToList();

I still  have 3 FavoriteBreweries join entities. (There are only two breweries in my sample database.)

Person 1 — FB — Brewery1

Person 2 — FB — Brewery2

Person 5 — FB — Brewery1

Now I ask for the beers that are made by the breweries

list = context.People.Include("FavoriteBreweries.Brewery.Beers").ToList();

In the lame little sample database, Brewery1 has 2 beers and Brewery2 has 0 beers.

I still get the same # of Favorite Breweries

Person 1 — FB — Brewery1 …Beer Count=2

Person 2 — FB — Brewery2 …Beer Count =0

Person 5 — FB — Brewery1 … Beer Count=2

Testing the same loading in .NET 4

In .NET 4, there has been a LOT of work done on the query generation. .NET 3.5 used a LOT of outer joins which was really messy. Much of this has been replaced with inner joins. But the outer join allowed the previous query to bring back the Favorite Breweries and Breweries even when the Breweries had no beers.

Using  a new version of the model that now includes foreign keys:

And running the same tests in .NET 4.0 where I”m getting the benefit of the new query processing, the query results change.

It is only when I eager load beers (where I know I have an empty collection for one of the breweries).

Here are the results:

Person 1 — FB — Brewery1 …Beer Count=2

Person 5 — FB — Brewery1 … Beer Count=2

The inner join prevented the database from discovering Brewery2.

I tested the same type of eager loading but this time using a many to many that does not include a join entity.

The results for an eager load that grabbed People.Include(“StoreLocations.Registers”) did not pick up the Stores with no registers.

This is definitely different than what we have learned to expect from querying. I would only expect the stores to be filtered out if I had explicitly added logic into my query to only retrieve stores with registers.

It’s a breaking change that, because it’s an edge case, I don’t expect to be modified by RC so you need to be aware of it.

I’ll probably just point to this blog post from my book rather than walking through the whole thing again.

Thanks Dave for pointing out the forum and to George Fitch who started the forum thread: “good catch!”.

Thanks to Danny Simmons‘ comment below clarifying that the provides that support EF3.5 will still work for EF4 "just without new provider affecting features like model first."

As far as I can tell, and confirmed by Fabio Pandolfo (@fabiopand on twitter) who is also on the hunt, DevArt’s Oracle provider might be the only 3rd party provider that is currently somewhat supporting EF4, though they are publically claiming Beta 2 support, not VS2010RC.  If you read this thread on their forums, you’ll see why I qualify that with “somewhat”.

If you have any clues about the status of other EF providers and their support for EF4, leave a comment here.