This is personal study note
Copyright and original reference:
https://www.youtube.com/watch?v=aS9FoCNlt3o&list=PLuHgQVnccGMDF6rHsY9qMuJMd295Yk4sa
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topic.title.MySQL represents 1st row as primary key
author_name, author_profile depend on "author_id"
"author_id" depends on "title"
This is "transitive dependencies"
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Copy "transitive dependencies" part and create author table
And create topic table with "author_id"
And remove duplicate