ER图里有一个标记看不懂
看到一张ER图
然后这个符号看不懂是什么意思了
求各位解释一下这个符号在ER图里表示什么含义啊
回复内容：
看到一张ER图
然后这个符号看不懂是什么意思了
求各位解释一下这个符号在ER图里表示什么含义啊
为了表现层级关系吧？不过层级一般是 one to many 的，这个画成 one to one 了，是失误还是别的意思，我也不知道。通常我标识 pid 的时候会用类似的方式。比如下面的：
表示 parent has more users 或 user belongs to parent
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