[Oracle] 카테고리 별 상품 개수 구하기 (Lv.2)

 

 

* 카테고리 별 상품 개수 구하기 (Lv.2)

SELECT CATEGORY
     , COUNT(PRODUCT_CODE) AS PRODUCTS
  FROM (
      SELECT SUBSTR(PRODUCT_CODE, 0, 2) AS CATEGORY
           , PRODUCT_CODE
        FROM PRODUCT
       )
 GROUP BY CATEGORY
 ORDER BY CATEGORY ASC