如何为一个表映射类之间的关系（@ManyToMany） [英] How to mapping the relations between classes (@ManyToMany) for a table

问题描述

如何映射三个类之间的关系@ManyToMany单向表的一个唯一表？

关系如下：

• 项目有许多任务


• 许多任务都有很多特定的活动（对标准） - 对于每个任务都有许多特定的活动


• 任务和活动对数据库是标准的。

所以，当我创建一个项目时，我'b
$ b

我会创建一个表（project_task_activity_map），像这样：

pre> project_id task_id activity_id
1 2 3
1 2 4
2 1 2
2 1 1
2 2 3
2 3 5


如何映射类Project？

参考链接：

查看订单表

解决方案

我认为层次结构像

项目
|
任务
|
Activity

Project& amp;活动。

更好地为Task&活动，仅将Project保留为主人。
共计4张表
- 项目
- 任务
- 活动
- TaskActivityMapping

第四个表格将会由任务和活动的Hibernate映射通过Embadable创建。

How to mapping the relations between three class @ManyToMany unidirectional for a unique table ?

The relations is like that:

• Project have many Task
• Many Task have many specifcs Activitys (to standard) - for each task have many specifcs activitys
• Task and Activitys are standard into the data base.

So, when I'll create a Project, I'll chose somes Tasks and somes Task's Activitys.

I would to create a table (project_task_activity_map) like that:

 project_id     task_id    activity_id
    1            2           3
    1            2           4
    2            1           2
    2            1           1
    2            2           3
    2            3           5 

How can I map the class Project ?

Reference link:

See Orders Table

解决方案

I think hierarchy like

Project | Task | Activity

There is no direct relation between Project & Activity.

Better to create many to many table for Task & Activity, keep Project as master only. Total 4 tables - Project - Task - Activity - TaskActivityMapping

Fourth table will be created by Hibernate mapping of Task and Activity via Embadable.

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