SQL Query for Inactive Users

Question

I have table which tracks user activity in a game. Activity information is stored into category and sub-category fields. For every activity that the user performs, a record gets created in the this table. Now I want to find the users who are inactive for the last 30 days.

Table Columns

• ID
• Username
• Group_name
• Activity_Category
• Activity_Subcategory
• Activity_Date

Please let me know if more information is required.

Answer 1

Use aggregation:

select user_name
from t
group by user_name
having max(activity_date) <= current_date - interval '30 day';

Note that date/time functions are highly database specific. So this exact syntax may not work in your database, but the idea should work.

If you have a separate table of users, it is probably faster to use not exists :

select u.*
from users u
where not exists (select 1
                  from activity a
                  where a.username = u.username and
                        a.activity_date <= current_date - interval '30 day'
                 );

Answer 2

No activity within the last 30 days means the latest activity was over 30 days ago:

select user_name, max(activity_date)
from tab
group by username
having max(activity_date) < current_date - interval '30' day;