Yes, I agree with you guys. the Design is crap here, but my solution is for people who cannot change the whole design to add a new column to a table like this and to explain how the best way to traverse through a table to do this type of an update.

I am sure there are lot of people who were trying to do this type of thing and waited so long it to finish saying to themlesves "This is a very large table, no wonder it takes so long". This will help them to understand the underline operation bit better and approach it more efficiently next time.

And others who are designing the tables, now you know the troubles ahead if you didn't design it properly at the first time.