SQL select case when and group

Question

我有这个table

我想按年龄分组并统计性别类型

本案：

age <= 20 then 'Group <= 20'
age between 21-40 then 'Group 21-40'
age between 41-60 then 'Group 41-60'
age > 60 then 'Group > 60'

我试过这段代码，但出现错误：

%%sql
select customer_id, birthdate, extract('year' from current_date) - extract('year' from birthdate ) age
case when age <= 20 then 'Group <= 20'
when age between 21 and 40 then 'Group 21 - 40'
when age between 41 and 60 then 'Group 41 - 60'
else 'Group > 60' end gender
from dim_customer 
group by 1

有什么解决办法吗？提前致谢。

顺便说一句：我在 Python

中使用了这段代码

Answer 1

别名列未在 SELECT 中使用，但在 GROUP BY 和 ORDER BY 子句中使用。

-- PostgreSQL
SELECT t.*
     , CASE WHEN age <= 20 THEN 'Group <= 20'
            WHEN age BETWEEN 21 AND 40 THEN 'Group 21 - 40'
            WHEN age BETWEEN 41 AND 60 THEN 'Group 41 - 60'
            ELSE 'Group > 60' END gender 
FROM (SELECT customer_id, birthdate
           , extract('year' from current_date) - extract('year' from birthdate ) age
from dim_customer) t

请从urlhttps://dbfiddle.uk/?rdbms=postgres_11&fiddle=38c6ba05adc779aed3063e490bcc6376

检查

N.B.: 使用 date_part('year', current_timestamp :: DATE) - date_part('year', birthdate)年龄计算。

统计性别并按部分分组使用别名

SELECT CASE WHEN age <= 20 THEN 'Group <= 20'
            WHEN age BETWEEN 21 AND 40 THEN 'Group 21 - 40'
            WHEN age BETWEEN 41 AND 60 THEN 'Group 41 - 60'
            ELSE 'Group > 60' END gender
        , COUNT(t.gender) count_gender
        , COUNT(CASE WHEN t.gender = 'M' THEN 1 END) gen_male
        , COUNT(CASE WHEN t.gender = 'F' THEN 1 END) gen_female
FROM (SELECT customer_id, birthdate, gender
           , extract('year' from current_date) - extract('year' from birthdate ) age
           , date_part('year', current_timestamp :: DATE) - date_part('year', birthdate) age1
from dim_customer) t
GROUP BY CASE WHEN age <= 20 THEN 'Group <= 20'
            WHEN age BETWEEN 21 AND 40 THEN 'Group 21 - 40'
            WHEN age BETWEEN 41 AND 60 THEN 'Group 41 - 60'
            ELSE 'Group > 60' END

请检查 url https://dbfiddle.uk/?rdbms=postgres_11&fiddle=ad8af9dd9b82ede20452377615ca7fde

SQL select case when and group

SQL select case when and group

postgresql

grouping

case