MySQL: How to only select rows where 'set' column has all the values / none of the values -

i have set data type column in mysql table called category_list can contain 1 or more of following values: category 1, category 2.

first question:

to return rows both categories have been selected, use:

"where find_in_set('category 1', category_list) > 0 , find_in_set('category 2', category_list) > 0" 

this works fine. when have many categories statement becomes large. there easier/better way select rows categories have been selected?

second question:

to return rows none of categories have been selected, use query:

"where find_in_set('xyz', category_list) = 0" 

i make sure xyz not possible value in set.

this works ok, if add value xyz set @ later time, these queries break.

is there easier/better way select rows set column has no value?