SQL AVG: 示例 - SQL 教程

示例
示例数据库

#1

SELECT AVG(DISTINCT salary) FROM employees;

#2

SELECT ROUND(AVG(DISTINCT salary), 2) FROM employees;

#3

SELECT AVG(DISTINCT salary) FROM employees WHERE department_id = 5;

#4

SELECT AVG(salary) FROM employees WHERE job_id = 6;

#5

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

#6

SELECT e.department_id, department_name, AVG(salary) FROM employees e INNER JOIN departments d ON d.department_id = e.department_id GROUP BY e.department_id;

#7

SELECT e.department_id, department_name, AVG(salary) FROM employees e INNER JOIN departments d ON d.department_id = e.department_id GROUP BY e.department_id ORDER BY AVG(salary) DESC;

#8

SELECT AVG(employee_sal_avg) FROM ( SELECT AVG(salary) employee_sal_avg FROM employees GROUP BY department_id ) t;

表单列表

countries

SELECT * FROM countries;

departments

SELECT * FROM departments;

dependents

SELECT * FROM dependents;

employees

SELECT * FROM employees;

jobs

SELECT * FROM jobs;

locations

SELECT * FROM locations;

regions

SELECT * FROM regions;

SQL 查询

执行

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结果