SELECT * FROM cart WHERE user_id = #{userId} AND product_id = #{productId} SELECT c.id, c.user_id, c.product_id, c.quantity, p.name as product_name, p.price as product_price, p.image as product_image FROM cart c LEFT JOIN product p ON c.product_id = p.id WHERE c.user_id = #{userId} INSERT INTO cart (user_id, product_id, quantity, create_time, update_time) VALUES (#{userId}, #{productId}, #{quantity}, NOW(), NOW()) UPDATE cart quantity = #{quantity}, update_time = NOW() WHERE id = #{id} DELETE FROM cart WHERE id = #{id} DELETE FROM cart WHERE user_id = #{userId} UPDATE cart SET quantity = #{quantity}, update_time = NOW() WHERE id = #{id}