I am not sure going and having nothing including water is a good idea.
Some restaurants have minimum order amounts per person and you have to pay if you order or not (This might be stealing) or the waitress get no tip even though she probably asked you if you wanted anything more than once and you didnt order anything. She still had to set up your place and clean up after you
If you are unwilling to order the salad, I think the Coke or a Beer (If an appropriate situation – ie others are drinking a beer) might be a better choice