On Save Event

Question

Hello everyone,

I'm relatively new to programming in C# and i have a program I have been writing that i have come across a snag.

Basically, my program is connected to a MS Access database with a required field.  In it's current state if you fill in most of the fields w/o filling in the required field and try to save it, it crashes the program. 

Is there a way to tie in an on click event that would search for a null value, and pop up an error message informing the user to enter information is said field?  Im using Visual Studio 2008. 

The save command im talking about is the disk icon that is on the database navigation toolbar that appears when you drag your first data bound object to the Windows form.

Thanks for all the help in advance!

Bradley from Chattanooga, TN.