How to Update Multiple Rows

Hi, I am Saddam Hossain.
I am working on shopping cart project. In this project when any customer orders multiple products the quantity of the products have to be declined from the product table. I am having problem to do this.
Is there anyone who can help me ?

Welcome to Sitepoint Saddam Hossain.

You wouldn’t normally decrement the value, you would SUM the orders and then deduct this from a stock level.

deducting from stock level ~is~ decrementing the product value by the quantity of products

normally, a cart is only one order, but the order can be for multiple different products

I would deduct it only for display purposes though, not modifying it in the database.

i agree… until checkout, when you ~have~ to deduct it