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我有这样的关系。有Car桌子和CarGroup桌子。车组表里面放着汽车。我想要的是：当一辆车被移除时，如果它在一个车组内，它也应该像往常一样从那里移除。我在我的项目中使用 Spring 和 Hibernate（我有一个 PostgreSQL 数据库）。当我想移除一辆车时，我得到了这个错误：

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not delete: [com.aaa.bbb.ccc.Car#2]; SQL [delete from Car where a_id=? and st=?]; constraint [fkbc80f56cb1ece7b8]; nested exception is org.hibernate.exception.ConstraintViolationException: could not delete: [com.aaa.bbb.ccc.Car#2]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:656)
    org.springframework.web.servlet.FrameworkServlet.doDelete(FrameworkServlet.java:582)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:112)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:187)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:169)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)

我什至不能像往常一样从 pgadmin（postgresql 控制台）中删除汽车。当我写下：

delete from Car where a_id=2 and st=2;

我得到的错误如下：

ERROR:  update or delete on table "car" violates foreign key constraint "fkac80f56cb1ece7b8" on table "cargroup_car"
DETAIL:  Key (a_id)=(2) is still referenced from table "cargroup_car".

********** Error **********

ERROR: update or delete on table "car" violates foreign key constraint "fkac80f56cb1ece7b8" on table "cargroup_car"
SQL state: 23503
Detail: Key (a_id)=(2) is still referenced from table "cargroup_car".

CarGroup我班的代码部分：

 @ManyToMany(cascade = {CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH}, fetch = FetchType.EAGER)
    @JoinTable(name = "cargroup_car", joinColumns = @JoinColumn(name = "ADID"), inverseJoinColumns = @JoinColumn(name = "AID"))
    private Set<Car> cars;

编辑：我想要：当我移除一辆车时，我希望它被删除，即使它在一个汽车组下。我不想删除汽车组来删除汽车。如何更改 Java 端数据库设置（级联类型或将多对多更改为多对一和一对多等）来做到这一点？

PS：我没有写Java端代码。如果你解释它，你是受欢迎的。

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3 回答 3

1

您不能删除汽车，因为cargroup_car表中的一行引用了它。因此，您需要在删除汽车之前删除 cargroup_car 行。

于 2011-11-09T21:05:15.967 回答
1

您需要确保所有 CarGroup 的汽车集中都没有您要删除的汽车：

public void deleteCar(Car car) {
    for (CarGroup group : car.getCarGroups()) {
        group.getCars().remove(car);
    }
    session.delete(car);
}
于 2011-11-09T21:19:20.000 回答
0

只是一个猜测：尝试添加CascadeType.REMOVE

@ManyToMany(cascade = 
  {CascadeType.REMOVE, CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH}, 
  fetch = FetchType.EAGER)

或者还有其他选择：您可以更改数据库中的外键约束以级联删除从汽车到汽车组，尽管这样做可能很危险，这取决于您的业务逻辑。

于 2011-11-09T21:14:00.303 回答