SELECT AVG (DISTINCT E.salary) AS avrage
FROM aircraft AS A, certified AS C, employees AS E
WHERE A.cruisingrange > 1000
AND A.aid = C.aid
AND C.eid = E.eid
ms access不直接支持 DISTINCT 聚合函数内部的语法。这里的一个解决方法是取一个子查询的平均值，该子查询查找不同的薪资：
SELECT AVG(salary) AS avrage
FROM
(
SELECT DISTINCT E.salary
FROM (aircraft AS A
INNER JOIN certified AS C ON A.aid = C.aid)
INNER JOIN employees AS E ON C.eid = E.eid
WHERE A.cruisingrange > 1000
) t;
1条答案
按热度按时间yqhsw0fo1#
ms access不直接支持
DISTINCT聚合函数内部的语法。这里的一个解决方法是取一个子查询的平均值，该子查询查找不同的薪资：注意，我还将旧的隐式连接语法转换为现代的显式连接语法。这是目前编写sql的首选方法。