Given a dataset of customer interactions, write a SQL query to identify the top-performing product categories by daily active users at Zulily.
Count distinct non-null customers for each calendar date and product category. Return every category tied for the highest daily active user count.
Output
- One row per date and top-performing category, with columns
event_date, category_name, daily_active_users, and category_rank.
- Include only categories with the maximum daily count for that date, ordered by
event_date ascending and category_name ascending.
