MariaDB - AVG函数

SELECT AVG(aggregate_expression)
FROM tables
[WHERE conditions]; 

SELECT expression1, expression2, ... expression_n,
AVG(aggregate_expression)
FROM tables
[WHERE conditions]
GROUP BY expression1, expression2, ... expression_n; 

SELECT AVG(salary) AS "Average Salary"
FROM Employee2;

SELECT AVG(salary * 1.5) AS "New Average"
FROM Employee2; 

SELECT emp_id, AVG(salary) AS "Average Salary"
FROM Employee2
GROUP BY emp_id;