I would also like to comment on the download links presentation. You have them as "WMV WMV", etc - initailly I thought it was some kind of typo but when I hovered over them I found that one was for C# and the other was for VB. You need to present things in a more "user-friendly" manner with neat sub-headings as VB downloads and C# downloads so it is clear and neat!!!

thanks,

  Paulo Pereira

You have the order all mixed up and it doesn't read well.

Not sure yet if using Linq will be any faster at run time. Has anyone tested to see if the runtime is the same as with writing your own t-sql statement.

Anway good job so far on the videos.

Like a user types in his login name and password but he made a mistake while typing his password. Now when you run the linq query it will not return anything and will throw an error. I have tryed the DefaultIfEmpty and a few other default types. Now I maybe coding it all wrong? Don't really know because there is not much infor, available on the net yet. Maybe someday someone will post some examples on how to work around these simple but painful errors.

So if you want to use linq with a gridview, dropdown list and so on then Linq is great. But if all you want to do is to check a few values in a database or check to see if they are even in the database. Then save yourself the headache and use a t-sql query.

So I want to show a simple example on how to handle a null return or I should say how I needed to handle it in my code. In t-sql we could always use the reader.HasRows but in Linq you need to use DefaultIfEmpty, SingleOrDefault, or one of the other Defaults.

registerDataContext db = new registerDataContext();

       var users = (from user in db.userAccounts

                    where user.email == TextBox1.Text

                    select user).SingleOrDefault();

       //Check if users is null.

       if (users != null)

       {

           Label1.Text = string.Format("<h2>The email address <font color='red'>{0}</font> already exist!</h2>", TextBox1.Text);

       }

       else

       {

           Label1.Text = string.Format("<h2>The email address <font color='red'>{0}</font> does not exist!</h2>", TextBox1.Text);

       }

Another way of making this same query is.

       registerDataContext db = new registerDataContext();

       userAccount users = db.userAccounts.SingleOrDefault(p => p.email == TextBox1.Text);

       if (users != null)

       {

           Label1.Text = string.Format("<h2>The email address <font color='red'>{0}</font> is already exist!</h2>", TextBox1.Text);

       }

       else

       {

           Label1.Text = string.Format("<h2>The email address <font color='red'>{0}</font> does not exist!</h2>", TextBox1.Text);

       }

I hope this may save someone else from pulling out their hair.

CodeBehind="Default.aspx.vb" Inherits="LINQPart1._Default"

But the sample code also includes a “Default.aspx.vb” file which handles the vb code, in order for the samples to work and be editable change that to something like:

CodeFile="Default.aspx.vb" Inherits="_Default"

That is if you want to do the very same thing Scott is doing and follow along

After learning linq.

I thought about testing it..

I have a table with the following fields.

name[..varcher(50)..notnull]

title[..varchar(50)..notnull]

id[..primary key..increment +1..int]

I have a linq to sql classes named dataclasses.dbml

here is my query

Dim db As New DataClassesDataContext

       Dim p As New testing With {.name = "ad", .title = "adi"}

       db.testings.InsertOnSubmit(p)

       db.SubmitChanges()

Here is my error..

It crashes on db.SubmitChanges()

With this error...

The null value cannot be assigned to a member with type System.Int32 which is a non-nullable value type.

Please help.

How to setup and configure your "LINQ TO SQL Classes" to connect to the DB.