SQL query to add category to bunch of posts where post_content matches keyword

Question

I'm trying to figure out how to properly go about adding a category to a massive number of posts in a wordpress site, i prefer doing this directly in the database as it's faster and a good learning experience :)

Here's my mysql query so far:

SELECT *
FROM wpsite_posts
WHERE post_content like '%keyword%'

This lists all the posts i want to modify, but the trouble is the column for category is not in the same table as wpsite_posts

The category is in the table called wpsite_term_relationships

In the table wpsite_posts there's a colum called ID which is the data that has to match with column OBJECT_ID in the table wpsite_term_relationships

In table wpsite_term_relationships there's a column called term_taxonomy_id this column contains the category and tag id's for wordpress.

What i am trying to do is with one sql query, search table wpsite_posts column post_content find the 'keyword' in the post_content and then use the matching ID from post_content to look inside table wpsite_term_relationships for matches in the column object_id and when there's a match i want to add a new entry to column term_taxonomy_id with '5232'

5232 = the new category id i wish to have these posts inside.

Sorry for the long read, i have no idea how to better explain this, any mysql gurus able to take a crack at this?