How to make the table the default set up value from another table?

There is a link word has one category, there is a "categories" table and it is foreign key, word_id, how to make the default that was substituted word_id id value from the table words?
April 19th 20 at 12:38
1 answer
April 19th 20 at 12:40
word has one category
Use one table instead of two.

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