Imagine you're at a job interview for an SQL programming position when the interviewer challenges you to find the solution to a puzzle. You give it your best shot, attacking the problem from several angles, and when the time is up, you find yourself right where you started—with no solution. Years later, after giving more thought to the problem, you decide that the puzzle probably doesn't have a solution after all! That's what happened to Isaac Blank, a talented SQL programmer who kindly gave me permission to share his experience with you.

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