how to deal with a cry baby

Me

i try to tell her to wait. that i need to finish cleaning, eating, or whatever im doing but if i dont go with her exactly when she wants to then she will throw herself to the floor and thrash around screaming and crying at the top of her lungs. Ill just ignore her but it seems to not do anything. If i try to stop her and explain again, it makes her cry louder. Im at a lost.