Find all PC’s makers which doesn’t produce laptops

–Find all PC’s makers which doesn’t produce laptops

 

1. SELECT DISTINCT maker
FROM product WHERE
maker NOT IN (SELECT maker FROM product WHERE type =

‘LAPTOP’)
AND type = ‘PC’

 

2. SELECT DISTINCT p1.maker
FROM         product AS p1 LEFT OUTER JOIN
                      product AS p2 ON p1.maker = p2.maker AND p2.type =

‘Laptop’
WHERE     (p1.type = ‘PC’) AND (p2.maker IS NULL)