mysql - ER图中的三元关系中两两之间的联系如何表示?

Question

比如说船舶给货主运输货物, 这个三元关系如果不加映射基数的话，写出来应该是这样的：，但是一艘货船可以给多个货主运输多批货物，一个货主可以有多批货物要运输，也就是需要多艘船舶，所以船舶和货主之间的联系是多对多，船舶和货物的关系是1对多；但是一批货只能交给一艘货船来运输，一批货物只能有一个货主。 那么对于这种联系该怎么在ER图中体现呢？

Answer 1

In this example, the relationship between the cargo and the cargo owner is obviously much closer than the relationship between the ship and the cargo {owner, object}

The cargo owner has one-to-many (ownership) of the goods
Ship to cargo one-to-many (transportation)

Three yuan reduced to two yuan, over

Answer 2

Quantities are all many-to-many, and there is a ternary relationship between three entities. Associations can be used to indicate