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SQL Group By?Having????????

? SQL ????GROUP BY ? HAVING ?????????????????????????????????????????????????????????????????

1. GROUP BY ??????

GROUP BY ??????????????????????????????????????????????????? COUNT?SUM?AVG?MIN?MAX ??

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SELECT department_id, AVG(salary) FROM employees GROUP BY department_id;

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• GROUP BY ?????????????????
• ????????????????

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• ?????????????????
• ???????????????

2. HAVING ??????

HAVING ???? GROUP BY ??????????????????????? WHERE ??????????????

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SELECT department_id, AVG(salary) FROM employees GROUP BY department_id HAVING AVG(salary) > 8000;

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• HAVING ??? GROUP BY ?????
• ?????????????

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• ?????????????????
• ? WHERE ????????????

3. GROUP BY ? HAVING ???

4. ??????

??1???????????

SELECT department_id, month, AVG(salary) FROM employees WHERE year = '2023' GROUP BY department_id, month HAVING AVG(salary) > 10000;

??2??????????

SELECT department_id, SUM(salary) FROM employees GROUP BY department_id HAVING SUM(salary) > 50000;

??3?????????????

SELECT department_id, job_id, COUNT(employee_id) FROM employees GROUP BY department_id, job_id HAVING COUNT(employee_id) > 10;

5. ????

• GROUP BY ? HAVING ??????????????????
• HAVING ??????????? SQL ????? ==?!=?>?<?>=` ??
• ??? HAVING ????????? GROUP BY ???????

?????????????????? GROUP BY ? HAVING ??????????????????????