Question

I have two tables: product and sale. How can I write a SQL statement to deduct sale item from a product?

I tried

UPDATE product,
       sale 
   SET product = ( product.ProductQuantity - sale.quantity)

Answer 1

use this SQL statement

UPDATE product SET productquantity=(productquantity-(SELECT quantity FROM sale)) WHERE product_id={ some product id } 

I added WHERE product_id={ some product id } as you probably want to update specific product only