Mark Down Attributes

Hi I have this which I use to mark up products in the zen database.

UPDATE products_attributes SET options_values_price = options_values_price * 1.20;

Can somebody tell what I would do to mark prices down 20%

Would it be

UPDATE products_attributes SET options_values_price = options_values_price * 1.00;

UPDATE products_attributes SET options_values_price = options_values_price * 0.80;

UPDATE products_attributes SET options_values_price = options_values_price * 0.20;

Let's see ...

A Product that is 100.00

UPDATE products_attributes SET options_values_price = options_values_price * 1.20;
will change the Product to 120.00

A Product that is 100.00

UPDATE products_attributes SET options_values_price = options_values_price * 1.00;
will change the Product to 100.00 (same price)

A Product that is 100.00

UPDATE products_attributes SET options_values_price = options_values_price * 0.80;
will change the Product to 80.00

A Product that is 120.00

UPDATE products_attributes SET options_values_price = options_values_price * 0.80;
will change the Product to 96.00

A Product that is 100.00

UPDATE products_attributes SET options_values_price = options_values_price * 0.20;
will change the Product to 20.00