I was working on my database homework and I just completed the first question. I was wondering if anyone could check my answers quickly before I proceed to the next question. Thank you very much.
Though it doesn't strike me as a very fair question: "imagine what data might be in the database, and from that answer a question that can only be answered by looking at the data that we haven't given you".
I said ". Entity integrity states that primary keys cannot be null, and that there needs to be a proper value in the primary key field. Primary keys are used to identify individual rows in a table, and if for example ST_CODE was missing for a row in the STORAGE table, then there would be a violation."
>I said ". Entity integrity states that primary keys cannot be null, and that there needs to be a proper value in the primary key field.
The value also has to be unique.
Candidate keys can be any column where the values meet the requirements of a primary key, i.e. every entry is non-null and unique. You can't really answer "what columns are candidate keys" without knowing what values are in them.