mysql - sql中的平均函数在 View 中不起作用

Question

我想从包含字段(emp_code、emp_name、salary、Dept_code)的表名 Employee 创建一个 View

create view dept_avg_salary as select dept_code , avg(salary) as average 
   from employee 
   group by dept_code

虽然上面的查询运行良好，但是在average列中，每一行都存储了相同的值9999.9999。但是如果我运行查询

select dept_code ,  avg(salary) as average 
    from employee 
    group by dept_code

效果很好。 有人可以帮我吗

Answer 1

我无法复制这个结果(除非所有工资都相同)。考虑提供适当的 DDL，以便我们可以了解您的表是如何构建的...

CREATE TABLE employee(emp_code INT NOT NULL AUTO_INCREMENT PRIMARY KEY, emp_name VARCHAR(12) NOT NULL, salary INT NOT NULL, Dept_code CHAR(1) NOT NULL);

INSERT INTO employee VALUES
(1,'John',1000,'A'),
(2,'Paul',2000,'B'),
(3,'George',1000,'B'),
(4,'Ringo',3000,'A');

SELECT dept_code , AVG(salary) average FROM employee GROUP BY dept_code;
+-----------+-----------+
| dept_code | average   |
+-----------+-----------+
| A         | 2000.0000 |
| B         | 1500.0000 |
+-----------+-----------+

CREATE VIEW dept_avg_salary AS 
SELECT dept_code
     , AVG(salary) average 
  FROM employee 
 GROUP 
    BY dept_code;

SELECT * FROM dept_avg_salary;
+-----------+-----------+
| dept_code | average   |
+-----------+-----------+
| A         | 2000.0000 |
| B         | 1500.0000 |
+-----------+-----------+