数据库创建的视图怎么使用

CREATE TABLE employees (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    department VARCHAR(50),
    salary DECIMAL(10, 2)
);

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

SELECT * FROM department_avg_salary;

-- 创建表
CREATE TABLE employees (
    id INT PRIMARY KEY,
    name VARCHAR(100),
    department VARCHAR(50),
    salary DECIMAL(10, 2)
);

-- 插入示例数据
INSERT INTO employees (id, name, department, salary)
VALUES (1, 'Alice', 'HR', 5000),
       (2, 'Bob', 'Engineering', 6000),
       (3, 'Charlie', 'HR', 5500),
       (4, 'David', 'Engineering', 6500);

-- 创建视图
CREATE VIEW department_avg_salary AS
SELECT department, AVG(salary) AS avg_salary
FROM employees
GROUP BY department;

-- 使用视图
SELECT * FROM department_avg_salary;