Now I go into my program and it hasnt actually updated... I can't put a null in the column. What do I have to do to update the edmx properly? Thank you.
Choosing the Update Model from Database is the best method for updating your EDMX. There are certain properties that don't get updated on the Conceptual layer.
Ensure that your Store layer has been updated by viewing it in the Model Viewer toolbox. If the Store has properly been updated then you're okay, and your database is in sync. If so, go into the visual designer, click the field, go to properties, and update the NotNull property on the Conceptual side.