Martín,
>Say the clerk at the front updated the customer city and the one on the back updated the zip code, or in a more typical case, Alice updates the customer Region and Bob updates its Salesperson. Now, both updates are sent to DB, and you get a zip which don't match the city, or a Region not matching the SalesPerson.
Shame on you Martín. You should normilize your database! <s>
"The five senses obstruct or deform the apprehension of reality."
Jorge L. Borges?
"Premature optimization is the root of all evil in programming."
Donald Knuth, repeating C. A. R. Hoare
"To die for a religion is easier than to live it absolutely"
Jorge L. Borges