Visual Studio 2008

I got two(2) tables. Below are the details.

Table 1:

ID CODE
===========
1 AAA
2 BBB
3 CCC
===========

Table 2:

ID BranchCode
===============
1 AAA
2 BBB
===============

Using Visual Studio 2008 (VB), how can I inform the user (using a messagebox) that the CODE CCC from Table 1 doesn’t exist in the field BranchCode in Table 2?

Thanks in advance!.