Return Modified Fields in LinqDataSource

I have a LinqDataSource like this one :

<asp:LinqDataSource ID="linqDSUsers" runat="server" 
     ContextTypeName="Repository.BBDatabaseDataContext" 
     Select="new (UserID,FirstName,LastName)" TableName="Users">
</asp:LinqDataSource>

How can I convert it into this :

<asp:LinqDataSource ID="linqDSUsers" runat="server" 
     ContextT开发者_开发知识库ypeName="Repository.BBDatabaseDataContext" 
     Select="new (UserID,FullName = FirstName + LastName)" TableName="Users">
</asp:LinqDataSource>

Thank you very much in advance.

Select="new (UserID, FirstName + LastName As FullName)"