post_activity +---------+------------+-------+ | user_id | post_date | posts | +---------+------------+-------+ | 1 | 2023-01-01 | 3 | | 1 | 2023-01-02 | 2 | | 2 | 2023-04-10 | 1 | | 2 | 2023-04-11 | 4 | | 3 | 2023-05-05 | 5 | +---------+------------+-------+ ##### Scenario SQL data wrangling for user posting behavior analytics. ##### Question Given a table of daily post counts, derive each user's registration date (their first post_date). For every user, calculate the total number of posts made within their first 7 days on the platform. Compute the Day-7 retention rate: the proportion of users who posted on their 7th day relative to those who posted on Day-1. ##### Hints Use window functions, date arithmetic, group by, and conditional aggregation.