In our department, we've to send some reports at different times in the same month, for example, three the first day, one the fifteenth, three the last day...

This was a task assigned to my coworker, but it consumed a lot of time to modify and execute the required querys and write the reports in Excek with the results, so O was assignes to create a program that created the reports automatically.

I asked my coworker for the querys, a lot of times since he "forgot it", and once my program was fully completed him, I asked him to test it and tell me if he saw any errors, if the reports were done correctly, etc... And, twenty days later, when I asked him again, told me that everything was okay, so the whole months of July and August, the reports were done automatically.

Today we've receives a ton of emails about how the reports were not correct, how the information was incomplete and such.

Guess who gave me only half the querys requested. Now I've to do every single of them manually. While my manager rants.

Note to future self: Never trust that guy again, and always re-check everything he checks. This better be a lesson for the future.