vmart_query_01.sql

-- vmart_query_01.sql
-- FROM clause subquery
-- Return the values for five products with the
-- lowest-fat content in the Dairy department

SELECT fat_content
FROM (
  SELECT DISTINCT fat_content
  FROM product_dimension
  WHERE department_description
  IN ('Dairy') ) AS food
  ORDER BY fat_content
  LIMIT 5;

输出

 fat_content
-------------
          80
          81
          82
          83
          84
(5 rows)