如何按 CONCAT_WS 分组

Question

我正在尝试将concat_ws函数运行到group by ，但出现以下错误。 是否意味着 Hive 不支持concat_ws到group by ？ 如果没有，是否有不同的写法？

我在瀑布表中有以下记录（只有年、月和日）：

Year, Month, Date, 
2018, 08, 09 
2019, 09, 27
2017, 09, 27
2019, 02, 27
2019, 01, 27
2019, 01, 30
2019, 09, 27
2017, 09, 27
2019, 02, 27
2019, 01, 27
2019, 01, 30
..., ..., ...

有没有一种方法可以使用查询将我的记录分组到一些行中，从而将所有年、月和日组合在一起？

查询的最终结果将是两行：

realdate,num
2019-01-27, 4
2019-01-28, 23
2019-01-29, 34
2019-02-01, 8
2019-02-02, 4

我认为查询应该是这样的：

    select
        concat_ws('-', year, month, day) as realdate,count(*)
    from
        waterfall_table
    where
        concat_ws('-', year, month, day) between '2019-01-25' and '2019-02-10'
    group by  concat_ws('-', year, month, day)
    order by concat_ws('-', year, month, day) desc
    limit 100

Answer 1

请试试这个

select
  cast( ltrim( year) +'-'+ltrim( month) +'-'+ltrim( day ) as date),count(*)
from
    (select 2018 year ,10 month,25 day union select 2017 year ,11 month,10 
    union select 2016 year ,8 month,14 )t1
where
  cast( ltrim( year) +'-'+ltrim( month) +'-'+ltrim( day ) as date) between cast('2017-01-25' as date) and  cast('2019-02-10' as date)
 group by  year,month,day
order by  cast( ltrim( year) +'-'+ltrim( month) +'-'+ltrim( day ) as date) desc

Answer 2

如果我理解正确，你需要类似的东西：

SELECT CAST( CONCAT(`YEAR`, '-', `MONTH`, '-', `DATE` ) AS DATE ) AS realdate, COUNT(*) as num
FROM your_table
GROUP BY realdate

Answer 3

您可以在 GROUP BY 和 ORDER BY 子句中使用列别名

SELECT CONCAT_WS('-', year, month, day) as realdate, COUNT(*)
FROM waterfall_table
WHERE CONCAT_WS('-', year, month, day) BETWEEN '2019-01-25' AND '2019-02-10'
GROUP BY realdate
ORDER BY realdate DESC
LIMIT 100

Answer 4

Hive 对别名很挑剔。 尝试这个：

按realdate desc排序

Answer 5

在 ORDER BY 中使用别名：

with waterfall_table as
(
select stack(11,
'2018', '08', '09', 
'2019', '09', '27',
'2017', '09', '27',
'2019', '02', '27',
'2019', '01', '27',
'2019', '01', '30',
'2019', '09', '27',
'2017', '09', '27',
'2019', '02', '27',
'2019', '01', '27',
'2019', '01', '30') as (Year, Month, day)
)

select
        concat_ws('-', year, month, day) as realdate, count(*) as cnt
    from
        waterfall_table
    where
        concat_ws('-', year, month, day) between '2019-01-25' and '2019-02-10'
    group by  concat_ws('-', year, month, day)
    order by realdate desc
    limit 100;

结果：

OK
realdate        cnt
2019-01-30      2
2019-01-27      2
Time taken: 92.909 seconds, Fetched: 2 row(s)

这个 Jira 似乎相关： HIVE-1449