Today's question (by Steve Jones - SSC Editor):

The First Place Seeing the New Year

-- 1 SELECT TOP 1 [name] , MIN (tzi.current_utc_offset) OVER (ORDER BY tzi.current_utc_offset) FROM sys.time_zone_info AS tzi; -- 2 SELECT TOP 1 [name] , tzi.current_utc_offset FROM sys.time_zone_info AS tzi ORDER BY tzi.current_utc_offset; -- 3 SELECT TOP 1 [name] , tzi.current_utc_offset FROM sys.time_zone_info AS tzi ORDER BY tzi.current_utc_offset DESC; -- 4 SELECT TOP 1 [name] , tzi.current_utc_offset FROM sys.time_zone_info AS tzi ORDER BY CAST (REPLACE (tzi.current_utc_offset, ':', '') AS INT) DESC; 

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The AI Puzzle

Here is a T-SQL puzzle about New Year’s Eve that Copilot created for you:

-- You have a table called PartyGuests with the following columns: -- GuestID int, Name varchar(50), RSVP bit, ArrivalTime time, DepartureTime time -- The RSVP column indicates whether the guest has confirmed their attendance (1) or not (0) -- The ArrivalTime and DepartureTime columns store the time when the guest arrived and left the party, respectively -- Write a query to find the name and arrival time of the guest who arrived last before midnight -- Assume that the party started at 8:00 PM and ended at 2:00 AM -- If there is more than one guest who arrived at the same time, return all of them -- If no guest arrived before midnight, return 'No guest arrived before midnight' as the name and NULL as the arrival time

Here is a table definition and some sample data:

-- Create the PartyGuests table CREATE TABLE PartyGuests ( GuestID int PRIMARY KEY, Name varchar(50) NOT NULL, RSVP bit NOT NULL, ArrivalTime time NULL, DepartureTime time NULL ); -- Insert some sample data INSERT INTO PartyGuests (GuestID, Name, RSVP, ArrivalTime, DepartureTime) VALUES (1, 'Alice', 1, '21:15:00', '01:30:00'), (2, 'Bob', 0, NULL, NULL), (3, 'Charlie', 1, '22:45:00', '00:30:00'), (4, 'David', 1, '23:59:00', '01:00:00'), (5, 'Eve', 1, '23:59:00', '02:00:00'), (6, 'Frank', 1, '00:15:00', '01:45:00');

How many rows does this query return?

SELECT Name, ArrivalTime FROM PartyGuests WHERE ArrivalTime = ( SELECT MAX(ArrivalTime) FROM PartyGuests WHERE ArrivalTime < '00:00:00' )

I hope you enjoy this puzzle and have a happy new year!

Answer: 0 rows

Explanation: This puzzle, created by Copilot, actually has a problem. The query shown was part of the solution, but the AI misunderstands time. 00:00:00 is midnight, but it's the start of the day, not the end. Therefore, when you get the max of values less than this in SQL Server, you get null. This causes no rows to be returned. Happy New Year! (and be careful of AIs)

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