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foreign key
What is the purpose of foreign key? Lets say that we have 2 tables author and book: https://code.sololearn.com/ca7a2A3a23a9 Why we need the foreign key in the book table? Wouldn't be easier if we replace the `author_id` foreign key with `author_name` and we don't need the author table anymore? Let say I want to add a new book to the database, first I need to check if the author is in the `author` table if it isn't I have to add it and then add the book.
1 Respuesta
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If I got your question right, you are asking, why one should use foreign key.
Table: user
Name
Email
...
Table: post
Text
Date
Author (=user)
If you put table post Author = id, it works fine, but if you want to render the data later on, you would have to query two tables - or 100 tables - to get the data you want to render. (For example you.
want to render:
post.text and user.email)
But if you put a foreignkey you just query one table (post) and then you can access the data like:
post.text
post.author.email (author = user as foreignkey)
(That's what I think, to know about that :))