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#2
white_cxl2007-10-21 03:17
回复：（white_cxl）求助求助!~有人会画E/R diagram吗...
难道没人会画吗?55555
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大家有人会画E/R表吗?就是用矩形代表entity,用菱形代表relationship,用椭圆代表attributes的?
我们老师出了两道很短的小题可是我就是不会做啊...!!!
题目如下:
这是四个table,冒号后面的是它的attributes
countries: name, area, population, gdp ("gross domestic product")
cities: name, population, longitude, latitude
rivers: name, length
seas: name, max depths
老师让我们画两个E/R图
1.each river crosses one or several countries
2.each river ends in another river or in a sea
我不会啊!!~
谁能帮帮我?晚上就交了...555
