我早些时候问过这个问题，并被告知要查看映射依据。

I have 2 tables: A s_id(key) name cli type

B sa_id(key) s_id user pwd.

  
  So in Jpa I have: 

@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
getB(){...} }

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

因此，现在如果有，但是jpa尝试使用一些不存在的新列(s_s_id)来编写查询

@Entity
class A{
...
@OneToMany(fetch=FetchType.EAGER, mappedBy="s")
Collection<B> x;
}

@Entity
class B{
@ManyToOne
A s;
}

With these tables:
A 
s_id(key) name cli type

B
sa_id(key) s_id(the keys from A) user pwd.

我该如何执行OneToMany和ManyToOne的联接，这样就不需要新的列或者新的表？请给我一个例子。问题是在B表中缺少外键吗？

如果我遗漏了映射，则会在"字段列表"中得到"未知列't1.S_S_ID"。

如果我输入的是"字段列表"中的"未知列'S_S_ID'"，

解决方案

我找到了它，我需要添加@ JoinColumn并给它起个名字...