Yesterday, we explored a puzzle that received a great response from our readers. Interestingly, not many were able to solve it correctly. If you haven’t seen the puzzle yet, I recommend you take a look at it here before reading the answer.
The puzzle involved selecting all the people from the “PersonColor” table who either have the same color as the “ColorCode” or have more colors than the “ColorCode” table. Let’s dive into the solution:
SELECT Name
FROM PersonColors pc
INNER JOIN SelectedColors sc ON sc.ColorCode = pc.ColorCode
GROUP BY pc.Name
HAVING COUNT(pc.ColorCode) >= (SELECT COUNT(ColorCode) FROM SelectedColors)
In this solution, we use an inner join to combine the “PersonColors” and “SelectedColors” tables based on the matching “ColorCode” values. The GROUP BY clause is then used to group the results by the person’s name. Finally, the HAVING clause filters the results to only include those individuals who have a count of colors greater than or equal to the count of colors in the “SelectedColors” table.
If you’d like to download the complete script for this interview question, you can find it here. The script includes the creation of the “PersonColors” and “SelectedColors” tables, as well as the insertion of sample data.
Understanding how to join tables and use aggregate functions like COUNT is essential in SQL Server. By mastering these concepts, you’ll be able to manipulate and analyze data effectively.
Feel free to share your thoughts and opinions about this puzzle in the comments section below. Happy coding!