SQL query to change categories

I have 26 different categories in ServiceDesk Plus. I would like to remove all 26 categories and replace them with 10 new categories. My plan is to add the 10 new categories, then run a SQL query to remap the old categories in requests to the new categories.

For example: in my old category list, I had three different categories for printers: "Desktop printers", "Office printers", "Mobile printers". I want to have a new category just called "Printers", but I want all the previous printer requests (even closed ones) to be moved into this one new "Printers" category. Does this make sense?

Can I just run a SQL query and change the category IDs of these three categories to the new category ID? Will this cause a problem elsewhere?

Thanks very much for any help!
Gavin