Backing up post and catogory

Sure, you can use the cli described here:
https://developer.www.ads-software.com/cli/commands/db/
See wp db query and access your file.

This seems like a good starting point:
https://melissafreeman.com.au/wordpress-sql-query-output-post_title-categories-tags/

@corrinarusso is there any other beginner friendly way to do it?

i mean like a step wise guide or so

I guess a better question for me would be what are you trying to accommplish?

Why do you want a “sql backup of post and their linked categories with url”?
Are you going to do something with the file?

actually i have a friend of mine who has got a WordPress site with over 28,000 post and 60+ categories. Now he asked me to migrate all those post with category to a custom cms whhich has got a simple cms.

I can figure out posts but can figure where and how the categories and featured image for those post are related.

A custom CMS?
But you have access to the db schema, yes?

With that amount of data, and the fact you have requested a more ‘beginner solution’, I would use WP All Export tbh:
https://www.wpallimport.com/documentation/export/export-posts-with-their-taxonomies/

Works well every time, and has a very strong support team.

You can get the file into something delimited, then use an import on the custom CMS.

Otherwise, you’ll not get much more easy than this imo:
https://melissafreeman.com.au/wordpress-sql-query-output-post_title-categories-tags/