Creating a database

That’s not the “WordPress way.” Most likely, you should be creating a custom post type to represent the thing you want to hold in your database, rather than building a whole DB system as a stand-alone.

There are many plugins to help you with creating the post types and managing custom fields and metaboxes.

Thanks
I had a look at some plugins that deal with Custom types, but cannot figure out how to use them to build a database
Can you please make a simple example? For example if I need to create a database of book references, with book title, author’s name and a book description for each book
and then display the database interface in the front end, how would it work?
How would I fill the database?
Regards

You’d create custom post type, “Book” and, maybe, another custom post type “Author” using the function “register_post_type” (see https://generatewp.com to get the code). Using the plugin Advanced Custom Fields, you’d add custom fields to the Books post type to relate Authors to Books and whatever other custom fields you’d need. The rest is simply a matter of coding single-book.php, single-author.php, and the related archive pages.

https://www.advancedcustomfields.com/resources/relationship/
https://www.advancedcustomfields.com
https://codex.www.ads-software.com/Post_Types
https://developer.www.ads-software.com/themes/basics/template-hierarchy/

Or you could find a plugin that has it all done already. https://www.ads-software.com/plugins/search/books+authors

This plugin might help you:
https://www.ads-software.com/plugins/custom-searchable-data-entry-system/