Almost every reporting question is a date question: revenue by month, signups in the last 30 days, days between an order and its delivery. Getting it right means truncating timestamps to the right grain, extracting parts with EXTRACT, formatting with TO_CHAR, and doing arithmetic with intervals rather than subtracting raw strings. These questions work with real timestamp columns so the edge cases, month boundaries and time zones behave the way they do in production.
What you will practice
•Group by month or week by truncating the timestamp instead of formatting it as text
•Pull out a year, month, quarter or weekday with EXTRACT for cohort and seasonality analysis
•Add and subtract intervals to build rolling windows such as the last 7 or 30 days
•Measure the gap between two timestamps in days, hours or months
•Format dates for output with TO_CHAR while keeping the underlying column sortable
