在HIVE中选择每月的第一天 [英] Selecting the first day of the month in HIVE

问题描述

我正在使用Hive(与SQL相似，但是对于SQL用户，语法可能没有什么不同).我看了其他的stackoverflow，但是它们似乎在SQL中具有不同的语法.

I am using Hive (which is similar to SQL, but the syntax can be little different for the SQL users). I have looked at the other stackoverflow, but they seems to be in the SQL with different syntax.

我正在尝试通过此查询获取每月的第一天.这给了我今天的一天.例如，如果今天是2015-04-30，则结果将是2015-04-01.谢谢！

I am trying to the get the first day of the month through this query. This one gives me today's day. For example, if today is 2015-04-30, then result would be 2015-04-01. Thanks!

select 
    cust_id,
    FROM_UNIXTIME(UNIX_TIMESTAMP(),'yyyy-MM-dd') as first_day_of_month_transaction
--DATEADD(MONTH, DATEDIFF(MONTH, 0, GETDATE()), 0) as first_day_of_month_transaction --SQL format. Not compatible in Hive.
from 
    customers;

推荐答案

要获取每月的第一天，可以使用:

To get the first day of the month, you can use:

date_add(<date>,
         1 - day(<date>) )

应用于您的表情:

date_add(FROM_UNIXTIME(UNIX_TIMESTAMP(), 'yyyy-MM-dd'),
         1 - day(FROM_UNIXTIME(UNIX_TIMESTAMP(), 'yyyy-MM-dd')) 
        )

但这将适用于任何格式正确的列.

But this will work for any column in the right format.

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