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Pattern

Date & time

13 problemsin this pattern, climbing easy → medium → hard. Pick wherever you're calibrated.

EZ

Easy

0 / 5 solved

Paid orders in a date window
SQL · ~5 min
NEW
Order count per day in May 2026
SQL · ~5 min
NEW
Customer tenure in days
SQL · ~5 min
NEW
Name the weekday of each login
SQL · ~5 min
NEW
Extract year and month number
SQL · ~5 min
NEW

MD

Medium

0 / 5 solved

Paid revenue per ISO week
SQL · ~6 min
NEW
Daily orders zero-filled for every day in range
SQL · ~8 min
NEW
Events per 15-minute bucket
SQL · ~6 min
NEW
Days between consecutive logins
SQL · ~8 min
NEW
Year-over-year revenue change
SQL · ~10 min
NEW

HD

Hard

0 / 3 solved

Customer × day activity grid
SQL · ~12 min
NEW
Revenue by fiscal year and fiscal quarter
SQL · ~12 min
NEW
Longest consecutive-day login streak
SQL · ~13 min
NEW