user实体
@ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE },
fetch = FetchType.LAZY)
@JoinTable(name="T_USER_ROLE", joinColumns={@JoinColumn(name="userid")},
inverseJoinColumns={@JoinColumn(name="roleid")})
private Set
------------------------------------------------
role实体
@ManyToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE },
fetch = FetchType.LAZY, mappedBy="roles")
private Set
select * from B where B.bid=(select bid from C where C.aid=A.aid);
再看看别人怎么说的。