How to properly collect php request to display content by id?

Question

SQL

There are 2 columns in the database:
site_category and site_news
The site_category contains the categories I created and recorded by type:
The category column contains entries of this type:

name -> Химия
category_id -> 1
------------------------
name - > Физика
category_id -> 2

i.e. there are 2 records in the database with two categories that have their own id

. And the site_news column with news contains the following records:

title -> Заголовок первой новости
category -> 1,2

And so on. That is, the news can have several categories and they are assigned by id.
Question:
How to correctly form an sql query to display news for the category selected in the select list?
For example, I chose to display only the "Chemistry" category in the list, and so on.

Answer 1

What subd? What is the category column type in site_news?
Your scheme is not normalized, on bare SQL it will not be possible to compose a query normally, most likely.

Answer 2

If the database is MySQL, then you can do this:

/* 1 - id категории "Химия" */
SELECT * FROM `site_news` WHERE FIND_IN_SET('1', `category`);

MySQL - FIND_IN_SET