想要一個SQL按值的範圍在oracle中分組值

Question

我有一個表t1並且有一列名爲days，所以我想將這些天分組1天到5天，6-15天和超過15天，然後計算每個組的計數，但是我不知道如何編寫sql，誰能告訴我？結果應該看起來像下面：

Number Scope(days)  
    5  1-5 
    7  6-15 
    10  15+ 

Answer 1

如果我沒有理解好，這可能是一個辦法：

with t1(days) as ( 
    select 1 from dual union all 
    select 2 from dual union all 
    select 5 from dual union all 
    select 6 from dual union all 
    select 7 from dual union all 
    select 8 from dual union all 
    select 10 from dual union all 
    select 11 from dual union all 
    select 16 from dual union all 
    select 17 from dual union all 
    select 19 from dual union all 
    select 19 from dual 
) 
/* the query */ 
select count(*), 
     case 
     when days between 1 and 5 then '1-5' 
     when days between 6 and 15 then '6-15' 
     else '+15' 
     end  
from t1 
group by case 
     when days between 1 and 5 then '1-5' 
     when days between 6 and 15 then '6-15' 
     else '+15' 
     end 

給出：

COUNT(*) CASE 
---------- ---- 
     3 1-5 
     4 +15 
     5 6-15 

的想法是被什麼東西聚集那就是說每個數字所在的「組」，並且您可以使用CASE輕鬆構建這樣的信息。

Accordin到Jarlh的建議，這可以被改寫爲

select count(*), the_group 
from (
     select case 
       when days between 1 and 5 then '1-5' 
       when days between 6 and 15 then '6-15' 
       else '+15' 
       end the_group 
     from t1 
    )  
group by the_group 

顯然，這假設你只有正數。