嗨,大家做了一些更多的修改,如何做到以下几点:
删除属于"A Wilks"的甲壳虫
person (driver-id, name, address)
car (license, model, year)
accident (report-number, date, location)
owns (driver-id, license)
participated (driver-id, car, report-number, damage-amount)
这是我想出的:
DELETE FROM car
WHERE model = 'beetle'
但是我知道这是错误的,因为它会删除所有的甲壳虫汽车,而不仅仅是A Wilks拥有的汽车.
嘿伙计们我正在做一些考试修改,并通过过去的论文可以有人告诉我,如果我在正确的轨道上.
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)查找2004年拥有涉及事故的汽车的总人数.
这是我想出的:
SELECT COUNT(driver-id)
FROM participated
WHERE participated.reportnumber=accident.reportnumber
AND accident.date = 2004
我是在正确的轨道上吗？任何帮助,将不胜感激.