SELECT sum( case when `tags_Column` CONTAINS 'tag2' then 1 else 0 end ) as tag2,
       sum( case when `tags_Column` CONTAINS 'tag3' then 1 else 0 end ) as tag3,
       .....
       sum( case when `tags_Column` CONTAINS 'tag256' then 1 else 0 end ) as tag256,
       sum( case when `tags_Column` CONTAINS `tag2` OR 
                      `tags_Column` CONTAINS 'tag3`
            then 0 else 1 end ) as doesnt_contains_tags_2_3
FROM `TableContainsTags`