This advanced SQL exercise is part of the book: Advanced SQL – Practical Techniques and Use-Cases, which includes more than 100 day-to-day SQL challenges (and solutions), need-to-know advanced features, and key concepts.


Here’s a challenging question, sent by Elad Peleg.
The following table contains a list of numbers :

 id int


Use a SQL query to convert each digit to a word


Quite simple, right 😉 ? Your solution should be applicable to any given number of rows and digits, and again – the real challenge is to solve it by using SQL only. (No variables, Procedures etc.)


Want to take the challenge to the next level ? How you would you SUM the digits of each number (using different method than what already posted) ? For example :