Sql sentence

Hello, I'm having a serious issue, I need to update (set them to 0) the prices of every product with price is more than x.
The reason that my business is of importations and the exchange rate went up really bad, so for expensive products I just can't sell them on their current prices.
So if I'm right the best way to do it is with a sql sentence, but I'm afraid of doing things wrong because I don't know about sql. I just know that I should use update and if commands...

I need to set those prices to ' 0 because I have a module that when prices are 0 it doesn't show the price and you can ask for a quote instead of buying, so that is going to solve my problem.

Hope someone can help me with this.... Last time I made something on phpmyadmin it went bad... So I hope you understand.

Thanks

change accordingly

Thanks very much!

welcome