sql_join_case when示例_統計金額

sql_join_case when示例_統計金額

統計每個time下每個type的金額

select 
    time,
    type
    sum(price)
from purchase a 
 join
    purchase_commodity b
where a.user=b.user    
group by time,type    

統計食品（飲料，盒飯，麪包）和非食品（化妝品）的結賬金額

select 
     flag,
     sum(payment)
from     
     (
    select
    case  b.type
    when '化妝品' then '1'
    else '0' end flag,
    payment
from purchase a 
 join
    purchase_commodity b
where a.user=b.user
     )
group by flag;     

請寫出查詢代碼，統計每5歲爲一個年齡層，每個年齡層的人數（20歲到39歲的會員分開每5歲爲一個年齡層，其他年齡分類到‘其他年齡’）

select 
    flag,
    count(1)
    (
    select 
    CASE WHEN age >=20 and age <25 THEN '1'
    CASE WHEN age >=25 and age <30 THEN '2'
    CASE WHEN age >=30 and age <35 THEN '3'
    CASE WHEN age >=35 and age <40 THEN '4'
    ELSE '其他年齡' END flag 
from 
(
 --獲取年齡   
to_char(to_date(sysdate,'yyyy'))-substr(birthday,1,4) as age
from t_user    
)
group by flag