MySQL唯一ID或组合ID [英] MySQL unique id or combined id

问题描述

我的项目和开发人员程序具有以下结构:

I have the following structure for my project and developer program:

developer table
id
developer name
etc...

project table
id
project name
etc...

developer _project table
???

因为一个开发人员可以在多个项目中，而一个项目可以有多个开发人员，所以我必须创建一个新表，但是从我的阅读中得知，他们没有告诉我应该使用什么ID.

Because a developer can be in multiple projects and a projects can have multiple developer I have to create a new table but from what I read is they don't tell what id should I use.

如果我使用id自动递增+ user_id + project_id，因为id是主键，我会重复吗?

If I use an id auto increment + user_id + project_id will I have duplicate since the id is the primary key?

推荐答案

使用唯一的组合键:

CREATE TABLE `developer_project` (
 developer_id INT(10) UNSIGNED /* etc... */,
 project_id INT(10) UNSIGNED /* etc... */,
 PRIMARY KEY dev_project (developer_id, project_id)
);

如果创建ID，则可能永远不会使用它，因为您将在LEFT JOIN

If you create an ID you will probably never use it since you will query the developer_id and/or project_id in your LEFT JOIN

注意:确保列定义与developer和project表相同.

NOTE: make sure the column definitions are the same as the developer and the project tables.

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