MySQL 집계 함수

⬛ (예시) TABLE_NAME : people

id	name	class
1	deok_gu	4
2	sang_gu	4
3	jin_gu	6
4	bong_gu	3
5	jin_gu	3

 

◼ COUNT

 → 둘 이상의 문자열을 입력한 순서대로 합쳐서 반환해주는 함수.

형식) SELECT COUNT(column_name) FROM <tablename>;

ex) SELECT COUNT(name) FROM people;

COUNT(name)

5

 

◼ GROUP BY

 → 특정 컬럼을 기준으로 그룹화 해주는 함수.

형식) SELECT (column_name) FROM <tablename> GROUP BY (column_name);

ex) SELECT class, COUNT(name) FROM people GROUP BY class;

class	COUNT(name)
4	2
6	1
3	2

 

◼ MAX

 → 최고값을 반환해주는 함수.

형식) SELECT MAX(column_name) FROM <tablename>;

ex) SELECT MAX(class) FROM people;

MAX(class)

6

 

◼ MIN

 → 최저값을 반환해주는 함수.

형식) SELECT MIN(column_name) FROM <tablename>;

ex) SELECT MIN(class) FROM people;

MIN(class)

3

 

◼ SUM

 → 컬럼 내용들의 합산값을 반환해주는 함수.

형식) SELECT SUM(column_name) FROM <tablename>;

ex) SELECT SUM(class) FROM people;

SUM(class)

20

 

◼ AVG

 → 컬럼 내용들의 평균값을 반환해주는 함수.

형식) SELECT AVG(column_name) FROM <tablename>;

ex) SELECT AVG(class) FROM people;

AVG(class)

4.0000