3nf

So, I believe I have the understanding of Fully Functional Dependencies, and Partial Dependencies. I'll provide a brief explanation, in case I'm doing something wrong I don't end up too far down the rabbit hole. I am working with a table that has a composite Primary Key composed of two attributes, with a total of 10 attributes in the table, in 1NF form. In my situation, a fully functional dependency involves the dependent relying on BOTH attributes in my Primary Key. A partial dependency relies on either one of the attributes from the Primary key. A transitive dependency involves two or more

Can someone please explain the difference between 3NF and BCNF to me? It would be great if you could also provide some examples. Thanks. Mosty Mostacho The difference between 3NF and BCNF is subtle. 3NF Definition A relation is in 3NF if it is in 2NF and no non-prime attribute transitively depends on the primary key. In other words, a relation R is in 3NF if for each functional dependency X ⟶ A in R, at least one of the following conditions are met: X is a key or superkey in R A is a prime attribute in R Example Given the following relation: EMP_DEPT(firstName, employeeNumber, dateOfBirth,

I have read the quote : data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] . However, I am having trouble understanding 3.5NF or BCNF as it's called. Here is what I understand : BCNF is stricter than 3NF left side of any FD in the table must be a superkey (or at least a candidate key) So why is it then, that some 3NF tables are not in BCNF? I mean, the 3NF quote explicitly says "nothing but the key" meaning that all attributes depend solely on the primary key. The primary key is, after all, a candidate key until it is chosen to be our primary key. If anything is