https://programmers.co.kr/learn/courses/30/parts/17043
COUNT SELECT COUNT (*) FROM ANIMAL_INS
SELECT COUNT (*) FROM ANIMAL_INS
(COUNT, SUM, MAX등의 집계함수는 NULL은 제외하고 집계함)
DISTINCT SELECT COUNT (DISTINCT NAME) FROM ANIMAL_INS
SELECT COUNT (DISTINCT NAME) FROM ANIMAL_INS
[SQL] 프로그래머스 : 중복제거하기(SELECT, COUNT, DISTINCT)