group by range in mysql

Question

Table:   
new_table                                                    
user_number  | diff                  
     2       |  0                      
     1       |          


        

Answer 1

select 
case
when diff between 0 and 20 then ' 0-20'
when diff between 0 and 20 then ' 21-41'
when diff between 0 and 20 then ' 42-62'
when diff between 0 and 20 then ' 63-83'
when diff between 0 and 20 then ' 84-104'
when diff between 0 and 20 then ' 105-135'
else '136-156'
end; as 'range',
count(*) as 'number of users'


from new_table
group by range