Want to test-and develop-your SQL data-engineering skills? Do you fancy yourself pretty skilled at SQL and want to see just how sharp you are? Then check out this installment of the Code Challenges series, as instructor Harshit Tyagi presents a number of challenges requiring you to write SQL queries to solve problems and answer questions. The challenges start at a relatively low level of difficulty-column selection, filtering rows from data, sorting and grouping query results-and get progressively tougher, testing you on topics like handling missing and invalid data, calculating moving window average, and data transformations. The challenges are all a few minutes long, and use a single database, so you can jump around from challenge to challenge or watch the entire course. So, if you want to see if you're equal to the tasks, try out these SQL challenges.