How can I get the complete list of all book categories in the table?

Question

I have a "Books" table like this: I'm trying to make a SpringBoot application where all these books are listed, but you can filter them by category. To do this, I want to display a list of each category so the user can click on the category they want. What's a better way to get a list of this category? For example, in the case of the picture above, I want to display a list like this: XXX (only once) YYYZZZ

P粉745412116 · Answer

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@Query annotation @lemon provided the solution

@Query("SELECT DISTINCT category FROM Books")
List categories();

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