One school of thought that developers have about primary keys is to add an additional column to uniquely identify each record. Which is another school of thought? Primary keys should not be used at all.
A primary composite key should be used.
Find unique values already in the data.
A default identifier should be created.

Show that there is a language a ⚆ {0, 1} â— with the following properties: 1. for all x â a, |x| ≤ 5. 2. no dfa with fewer than 9 states recognizes a. hint: you don’t have to define a explicitly; just show that it has to exist. count the number of languages satisfying (1) and the number of dfas satisfying (2), and argue that there aren’t enough dfas to recognize all those languages. to count the number of languages satisfying (1), think about writing down all the strings of length at most 5, and then to define such a language, you have to make a binary decision for each string about whether to include it in the language or not. how many ways are there to make these choices? to count the number of dfas satisfying (2), consider that a dfa behaves identically even if you rename all the states, so you can assume without loss of generality that any dfa with k states has the state set {q1, q2, . . , qk}. now think about how to count how many ways there are to choose the other four parts of the dfa.

Describir textbook icon_person mira los dibujos y describe lo que está pasando. usa los verbos de la lista.

Jaina and tomas are being considered as new tenants in an apartment. the landlord looks at their creditworthiness because he wants to be sure his new tenant pays the rent on time and in full. the table below summarizes the information that was on their applications. application information questions jaina tomas how many years have you had your job? 5 2 what is your monthly salary? $1,850 $2,500 how many credit cards do you have? 4 1 how much debt do you have? $13,000 $7,000 how many times were you late with payments on credit cards in the past year? 5 1 who will the landlord decide to be more creditworthy and why? tomas because the ratio of his debt to income is less. jaina because she has had her job longer, which makes her look more stable. jaina because she has more credit cards available to her. tomas because he makes more money per month.