How to Get First Row Per Group in Snowflake

In Snowflake, we can get the data of the users and sessions along with the first session of all users of a particular day. To get that, we will utilise the “row_number()” Function. In this blog, we will learn to use the “row_number()” function and get the first session.

Snowflake - Get First Row Per Group

If we have tables that include the data about sessions and users and want to view first session of all the users for a specific day, we can use the “row_number()” function. Example for “row_number()” function:

select
us.user_id1,
us.session_id1,
s.start_date1,
s.end_date1,
row_number() over (partition by user_id order by start_date1 desc) as row_number
from user_sessions1 us
left outer join sessions1 s on s.id1 = us.session_id1
Where to_varchar(start_date1, ‘dd-mm-yyyy’) = ‘06-02-2022’

This provides every Session ID of the day and its row number. As we only require the second session of the day, we only require a row that has row_number: 2. To get that, we have to utilise the common table expressions

with cte_sessions1 as (
select
us.user_id1,
us.session_id1,
s.start_date1,
s.end_date1,
row_number() over(partition by user_id1 order by start_date1 desc) as row_number
from user_sessions1 us
left outer join sessions1 s on s.id1 = us.session_id
where to_varchar(start_date1, ‘dd-mm-yyyy’) = ‘09-01-2022’
)
select *
from cte_sessions1
where row_number = 2;

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Conclusion

The “row_number()” function is helpful for getting the required data, users, and sessions. I hope this provides you with the essential information about the “row_number()” function.

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Last updated: 04 Apr 2023
About Author

Kalla Saikumar is a technology expert and is currently working as a Marketing Analyst at MindMajix. Write articles on multiple platforms such as Tableau, PowerBi, Business Analysis, SQL Server, MySQL, Oracle, and other courses. And you can join him on LinkedIn and Twitter.

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