mysql - 根据模式在 MySQL 中查找拥有汽车的总人数

Question

嘿伙计们，我正在为考试做一些复习并浏览过去的试卷，有人可以告诉我我是否在正确的轨道上吗。

考虑下面给出的保险数据库:

person (driver-id, name, address)<br>
car (license, model, year)<br>
accident (report-number, date, location)<br>
owns (driver-id, license) <br>
participated (driver-id, car, report-number, damage-amount)<br>

1)求出 2004 年发生事故的汽车总人数。

这是我想出的:

SELECT COUNT(driver-id)
FROM participated
WHERE participated.reportnumber=accident.reportnumber
AND accident.date = 2004

我在正确的轨道上吗？任何帮助将不胜感激。

Answer 1

不，不对，你要引用accident表:

SELECT COUNT(`driver-id`)
FROM participated
INNER JOIN accident ON  participated.reportnumber = accident.reportnumber
WHERE accident.date = 2004