blocks|key|1103201|text|是的，您应该创建一个Meeting实体来表示Student和Supervisor之间的多到多关系。在它中，您可以使用对应于这些表的外键来关联这些表。在SQL中，它可能如下所示：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1103202|Create+table+Meeting+{
id+INT+NOT+NULL+PRIMARY+KEY+AUTO_INCREMENT,
student_id+INT+NOT+NULL,
supervisor_id+INT+NOT+NULL,
//rest+of+the+fields...+++
FOREIGN+KEY+(student_id)+REFERENCES+Student(id)
FOREIGN+KEY+(supervisor_id)+REFERENCES+Supervisor(id)
}|code-block|syntax|javascript|1103203|您还会对Supervise在Project和Supervisor之间做同样的事情。你也可以在你的会议表上使用一个名为复合键的东西，我想这可以归结为个人喜好，我通常是这样做的，当代表很多很多关系时。我并不是说这是你将要使用的语法，这取决于你的数据库，这只是一个指向正确方向的例子。希望能帮上忙。|1103204|此外，对于您的图表(我只是猜测这是针对一个类)，您可能需要查看一些软件，比如visio或可视化范例来创建ER图。虽然大多数人将能够理解您当前的图表，但这并不是正确的建模。|1103205|为了好玩，我根据你的表格做了一个图表：|1103206|📷|atomic|1103207|​|1103208|如果Supervisor和Project之间的关系是多到多的，您可能需要它们之间的一个实体。这被称为associative+entity。我给我的SupervisorProject贴上标签，只是为了让它们更清晰一些。|1103209|编辑忽略了学生和项目是一对一的事实，修正了这一点，对不起。|BOLD|1103210|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/a6048652c2b9aef470997c83d4a610a6.png|imageAlt^0|A|7|M|7|U|A|0|0|4|9|E|7|M|A|0|0|0|0|1|0|0|0|2|A|D|7|1E|I|21|H|0|0|2|0^^$0|@$1|2|3|4|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1G|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1H|8|@$9|1I|A|1J|B|C]|$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|1O|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1P|8|@]|D|@]|E|$]]|$1|Q|3|R|5|S|7|1Q|8|@]|D|@$9|1R|A|1S|1|1T]]|E|$]]|$1|T|3|U|5|6|7|1U|8|@]|D|@]|E|$]]|$1|V|3|W|5|6|7|1V|8|@$9|1W|A|1X|B|C]|$9|1Y|A|1Z|B|C]|$9|20|A|21|B|C]|$9|22|A|23|B|C]]|D|@]|E|$]]|$1|X|3|Y|5|6|7|24|8|@$9|25|A|26|B|Z]]|D|@]|E|$]]|$1|10|3|-4|5|6|7|27|8|@]|D|@]|E|$]]]|11|$12|$5|13|14|15|E|$16|17|18|-4]]]]

Yes, you should create a <code>Meeting</code> entity to represent the many to many relationship between <code>Student</code> and <code>Supervisor</code>. In it you can relate to those tables using foreign keys that correspond to the those respective tables. In SQL it may look something like this:
<pre><code>Create table Meeting {
id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
student_id INT NOT NULL,
supervisor_id INT NOT NULL,
//rest of the fields... 
FOREIGN KEY (student_id) REFERENCES Student(id)
FOREIGN KEY (supervisor_id) REFERENCES Supervisor(id)
}
</code></pre>
You would also do the same thing for the <code>Supervise</code> between <code>Project</code> and <code>Supervisor</code>. Also you could use something called a composite key on your Meeting table, I guess it comes down to personal preference, I usually do it this way when representing many to many relationships. I'm not saying this is the syntax you will use, that depends on your database, this was just an example to point you in the right direction. Hope it helps.
Also for your diagram (I'm just guessing this is for a class) you might want to look into software such as visio or visual paradigm to create your ER diagram. While most people will be able to understand your current diagram, that's not correct modeling.
For fun I made a diagram based on your tables:
<img src="https://i.stack.imgur.com/drNu5.png" alt="enter image description here" />
You would want an entity between <code>Supervisor</code> and <code>Project</code> if they are a many to many relationship. This is called an <code>associative entity</code>. I labeled mine <code>SupervisorProject</code> just so they are a little more clear.
Edit
Overlooked the fact that Student and project was a many to one, fixed that, sorry.

blocks|key|2179001|text|作为对Cohagen的回应，this+stackoverflow+post建议，即使关系表没有属性，也可以通过保留关系表来表示许多到许多关系的关系，比如Supervise。相反，Do表位于多到一个关系之间，没有属性，因此我们可以去掉它，只需在学生中向项目表添加一个外键引用。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2179002|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/7296846/how-to-implement-one-to-one-one-to-many-and-many-to-many-relationships-while-de^0|24|9|2H|2|E|N|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@$9|S|A|T|1|U]]|E|$]]|$1|F|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

In response to Cohagen <a href="https://stackoverflow.com/questions/7296846/how-to-implement-one-to-one-one-to-many-and-many-to-many-relationships-while-de">this stackoverflow post</a> suggests that many to many relationships like <code>Supervise</code> can be represented by keeping the relationship table even if it has no attributes. In contrast the <code>Do</code> table lies between a many to one relationship and doesn't have attributes so we can get rid of it and simply add a foreign key reference to the project table in students.

Currently trying to get to grips with SQL for the first time, so I am working through a few problems. Here is a sample database spec:

<blockquote>
 Students (name, gender, course) do projects(title). Each project has
 two supervisors (name, gender, department). All students do a project
 but not all projects get taken. More than one student can do the same
 project. Students meet one of their supervisors regular and these
 meetings are recorded (date, time, student, supervisor, notes).
</blockquote>

So far I've got an ER diagram drawn up which I think is correct:

<img src="https://i.stack.imgur.com/i5hmk.png" alt="enter image description here">

I can get the basics (e.g. creating a Student table etc) but I'm having trouble getting my head around how to represent the relationships, specifically the meetings relationship, and how to represent it and its attributes in SQL. Should I instead create a 'meetings' entity?

Translating relationship attributes from ER diagram into SQL

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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