I have this task to complete. The goal is to correct a lot of data corrupted in production by some bugs. The actual SQL is not too difficult. Understanding the business logic is most tricky. We had a meeting with the customer to confirm the requirements. Based on the first meeting I banged out a script in no time.Now I made sure I did my script right. The main routine just makes a lot of calls to other functions. Those functions are ones that I wrote myself. They are in the script as well. However the main routine just implements the logic calling other routines. All the routines trap exceptions and deal with them to ensure the script will run on.
Later we found out that there were some additional requirements for the script. Now the tough business logic became even tougher. However the way I set up the script helped make these new changes a breeze. There was a need for a new function or two. But the main script just needed a line or two tweaked. I had set myself up for success. With the time saved I assisted some other developers who were swamped with their full work loads. That's smart.
