SQL 집계 함수

SQL 집계 함수

1. SUM()

• department별 총합을 반환

SELECT department, SUM(salary) AS total_salary
FROM employees
GROUP BY department;

# 결과
+------------+--------------+
| department | total_salary |
+------------+--------------+
| HR         | 150000       |
| IT         | 200000       |
| Sales      | 250000       |
+------------+--------------+

2. AVG()

• department별 평균을 반환

SELECT department, AVG(salary) AS avg_salary
FROM employees
GROUP BY department;

# 결과
+------------+------------+
| department | avg_salary |
+------------+------------+
| HR         | 30000      |
| IT         | 25000      |
| Sales      | 25000      |
+------------+------------+

3. MIN()

• department별 최솟값을 반환

SELECT department, MIN(salary) AS min_salary
FROM employees
GROUP BY department;

# 결과
+------------+------------+
| department | min_salary |
+------------+------------+
| HR         | 25000      |
| IT         | 20000      |
| Sales      | 22000      |
+------------+------------+

3. MAX()

• department별 최댓값을 반환

SELECT department, MAX(salary) AS max_salary
FROM employees
GROUP BY department;

# 결과
+------------+------------+
| department | max_salary |
+------------+------------+
| HR         | 50000      |
| IT         | 40000      |
| Sales      | 30000      |
+------------+------------+

5. COUNT()

• department별 레코드 수를 반환

SELECT department, COUNT(*) AS employee_nums
FROM employees
GROUP BY department;

# 결과
+------------+---------------+
| department | employee_nums |
+------------+---------------+
| HR         | 5             |
| IT         | 8             |
| Sales      | 10            |
+------------+---------------+