-4

I want a simple pl/sql code that works on phpmyadmin to do the following. I have two tables, the first is called products and the second is called order. The two tables have a column with the name of quantity. When I add to the order table, the quantity from the products table decreases. The problem is that I want to make a trigger, see if I was adding an unavailable quantity in the products table, or see if the quantity in it is 0 and send me an Exception telling me that the quantity is not available, for example, please help me with this simple code because I did not find a simple solution for it

8