This is personal study note Copyright and original reference: https://www.youtube.com/watch?v=7meeyknh7yE&list=PLuHgQVnccGMDF6rHsY9qMuJMd295Yk4sa ================================================================================ In "topic" table, there is duplications It's caused due to "partial dependencies" ================================================================================ You can create following "non-duplicated row" table And you should create "topic_type" table ================================================================================ Other tables which had been created in first normal table