Built a deck that failed inspection three times then had to be demolished

I was going to save money by building my own deck. Bought all the lumber, rented tools, spent every weekend for two months on it. Failed the city inspection the first time for improper footings. Fixed it. Failed again for railing height. Fixed it. Failed a third time because the structural calculations were wrong. The inspector said it needed to be torn down. I paid $3,200 to demolish something I spent $7,800 building.