问题
This is a question about correctly "naming things". Specifically, how do you distinguish between:
- the "between" table in a many-to-many relationship (e.g.
users,users_questions,questions) - the (temporary) table that is created during a SQL
JOIN(e.g. 'SELECT * FROM users INNER JOIN users_questions.user_id ON users.id WHERE users_question.question_id=37016694;`)
回答1:
Lots of database designers use the term join table in your first sense: to implement a many-to-many relationship between entities. It's also called a junction table, association table, and other things. More info: https://en.wikipedia.org/wiki/Associative_entity
I've never heard the second sense used. (But, hey, I don't get out much. :-) If you're writing documentation, or teaching, I suggest you reserve the word table to mean an actual, physical, table. Avoid using the word table for a resultset unless you qualify it by saying virtual table or some such phrase. That way your readers and students won't waste time trying to find the definitions of these not-really-tables in your schema.
回答2:
From relational point of view, a JOIN table (a table which resolves many-to-many relationship) is real physical table. Else it wouldn't survive between requests. In my opinion, the term "join table" was coined by MVC "Code First" developers who ignore physical entities in the DB realm, especially if they are not shown in DbContext.
In my opinion, again, we should honor relational realities.
So help me Codd.
来源：https://stackoverflow.com/questions/37016694/is-a-join-table-the-result-of-a-sql-join-or-the-table-between-a-many-to-many