GROUP_CONCAT
STD
STDDEV_SAMP
모집단 표준편차를 반환합니다.
STD(expr)
아래 값을 입력하면 예제에 즉시 반영됩니다.
department_id
salary
salary_stddev
employees
SELECT department_id, ROUND(STD(salary), 2) AS salary_stddev FROM employees GROUP BY department_id;