Using SqlDependency for data change events: only the fields in SELECT are fired?

I am following this tutorial here: http://www.codeproject.com/KB/database/chatter.aspx of using SqlDependency for changing data changed.

After downloading the tutorial, it works fine with me.

However, If I have this query:

SELECT [Message] FROM dbo.[Message] JOIN dbo.Person ON id = [Message].Person_ID

The person table structure is: ID & Name. If I change the Name in the Person table, that will not holding contents in the [Message].Message but this ev开发者_运维问答ent is still fired.

So my question is how can this event only fired if there is a new message in the [Message] table? would this be possible to achieve?

Thanks in advance.