Calculating total

Write the query that computes the cart total.

Updating quantity

To change a cart line's quantity you use UPDATE. WHERE picks which row to update.

UPDATE cart
SET qty = 3
WHERE id = 1;

This query sets the quantity of line 1 to 3.

In cart, qty = 3 is updated. Only the rows where id = 1 holds are affected.

Changing quantity is the most common cart operation. Without WHERE every row updates; be careful.

Set qty to 3 for the line with id=1 in cart.

Show example solution

UPDATE cart
SET qty = 3
WHERE id = 1

New quantity

UPDATE cart
____ qty = 3
WHERE id = 1;

Show answer

UPDATE cart
SET qty = 3
WHERE id = 1;