JPA和2个简单表 [英] JPA and 2 simple tables

问题描述

我有2张桌子:

A
s_id(key) name cli type

B
sa_id(key) s_id user pwd

所以在Jpa 我有:

@Entity
class A...{
   @OneToMany(fetch=FetchType.EAGER)
    @JoinTable( name="A_B", 
    joinColumns={@JoinColumn(name="a_id", table="a",unique=false)}, 
    inverseJoinColumns={@JoinColumn(name="b_id", table="b", unique=true)} )
   Collection<B> getB(){...}
}

b类只是一个基本实体类，没有对A的引用.

class b is just a basic entity class with no reference to A.

希望这很清楚.我的问题是:我真的需要一个联接表来进行这种简单的联接吗?不能使用简单的joincolumn或其他方法完成此操作吗?

Hopefully that is clear. My question is: Do I really need a join table to do such a simple join? Can't this be done with a simple joincolumn or something?

推荐答案

您不需要JoinTable.如果B类没有引用A类，则满足以下条件

You do not need a JoinTable for this. If the class B has no reference to class A then the following will suffice

@Entity class A...{ 
@OneToMany(fetch=FetchType.EAGER)     
Collection getB(){...} }

在大多数情况下，尽管您可能需要双向关系，在这种情况下B引用了A.在这种情况下，您将需要查找@mappedBy批注.保罗提到的.

In most cases though you may want a bidirectional relationship in which case B has a reference to A. In that case you will need to look up the @mappedBy annotation. mentioned by Paul.

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