Daily SQL and Python Challenges for Data Engineers
Daily Data Engineering Challenge - 2026-05-16
A fresh SQL and Python challenge every day. Practice data engineering skills with adaptive difficulty that matches your level. Track your accuracy, build streaks, and find your weak spots.
Today's SQL Challenge: No Gaps
The email marketing team is preparing a campaign blast and needs a clean contact list with no blank fields. For each user, show their username, email address (substituting 'unknown' if the email is missing), and age bucket (substituting 'unspecified' if the age bucket is missing). Only include users whose account is currently active.
Today's Python Challenge: Transpose Table
Given a 2D matrix (list of rows, each row a list), return its transpose where element [i][j] becomes [j][i]. Assume all rows have the same length.