I have a table with three fields, FirstName, LastName and Email.
Here\'s some dummy data:
FirstName | LastName | Email
Adam West adam@west.c
Stefan's answer is correct. To probe a little bit deeper you need to know that NULL is not the same as Nothing. Null represents the absence of a value, or in other words, not defined. Nothing represents an empty string which IS in fact a value.
Undefined + anything = undefined
Good database tidbit to hold onto!