select 
    case 
    when price between 0 and 3 then 1
    when price between 3 and 6 then 2
    when price between 6 and 10 then 3
    end,
    count(*)
from 我有一个表A
group by     case 
    when price between 0 and 3 then 1
    when price between 3 and 6 then 2
    when price between 6 and 10 then 3
    end