Return Single Value

Hello,

I created a stored procedure which selects a value according to
ContentId.
I know that will be only one value returned or none.

So if a record is found I want to return the string contained in
ContentHtml.
Else I want to return the string "NotFound"

Could somebody help me out with this?

Here is my present stored procedure:

-- Specifies the SQL-92 equals compliant behavior
SET ANSI_NULLS ON
GO

-- Specifies the SQL-92 quotation mark rules
SET QUOTED_IDENTIFIER ON
GO

-- Alter procedure
ALTER PROCEDURE [dbo].[by27_Content_GetContent]

        -- Define the procedure parameters
  @ContentName NVARCHAR(100),
  @ContentCulture NVARCHAR(5)

AS

-- Prevent extra result sets from interfering with SELECT statements.
SET NOCOUNT ON;

-- Declare and define ContentId
DECLARE @ContentId UNIQUEIDENTIFIER;
SELECT @ContentId = ContentId FROM dbo.by27_Content WHERE ContentName =
@ContentName

-- Check if ContentId is Not Null
IF @ContentId IS NOT NULL
  BEGIN

                -- Select localized content from by27_ContentLocalized
                SELECT dbo.by27_ContentLocalized.ContentHtml
                FROM dbo.by27_Content
    INNER JOIN dbo.by27_ContentLocalized
      ON dbo.by27_Content.ContentId =
dbo.by27_ContentLocalized.ContentId
                        WHERE (dbo.by27_ContentLocalized.ContentCulture = @ContentCulture
AND dbo.by27_Content.ContentName = @ContentName);

  END

-- Create procedure
GO
Thanks,
Miguel