oracle - When should I use a nested table and when a reference? -

how should decide whether use nested table or reference?

for example:

we have airline , flights table:

create table airline of airline_ty( token varchar2(8), description varchar2(20) )  create table flights of flights_ty( flightnumber number(10) securitylevel varchar2(10) ) 

should know make reference in airline (flights ref flights_ty) or go nested table?

it depends on requirements usage of data. in example airlines , flights flight should have foreign key airline. main table flights , airlines codebook.

an example case nested table choice:
customer in core banking application has several phone numbers, email addresses etc. need hold data customer, not evaluate (all customers email etc.), display other customer detail. cannot have table each 1 many property, because have more interesting data, accounts, loans, credit cards, account statements, behavior score cards etc.

you have take account, redundancy, reuse, importance, property vs. entity, aggregation vs. composition...