a bit of a dumb questions I'm sure

I'm trying to allow user to set an item to be default. I've got a function that run a query to first find the current default item. Then runs a second query that unsets the current default item. Then a third query runs to set the new user selected item to be the default.

This seem to work fine when a default item has been perviously selected, but when I try to set the default item initially I get the good old "Cannot access a property or method of a null object reference." error.

This is because the first query that runs returns no items I'm sure. So I need to write an if statement that if the first query returns nothing to skip the second and go right to the third.

The only problem is I can't make a reference to a null object.

So how do I go about writing this statement.

Thanks