CECS 323 FINAL STUDY GUIDE
Database Index - Answers -A Data structure that the database uses to find records
within a table more quickly. Indexes are needed because they are used to quickly find
data without having to search through every row in the table everytime the database
table is accessed.
ACID - Answers -contains the properties of a database transaction and it is meant to
guarantee the validity of the transaction in the event of errors or power failures.
Atomicity - Answers -Each transaction is all or nothing. If one part of the transaction
fails, then the entire transaction fails and the database is left unchanged.
Consistency - Answers -The database is valid from one state/transaction to the next.
Any Data written to the database must be valid according to the defined
rules/constraints
Isolation - Answers -Concurrent execution of transactions result in a system state that
would be obtained if the transactions were sequential. I.E. what is a visible to users and
to users/system during sequential transaction execution.
Durability - Answers -Once a transaction is committed, it will remain so even in the
event of power loss, crash, or error.
First Normal Form - Answers -eliminate multi-valued and repeated attributes
Second Normal Form - Answers -Eliminate subkey, where the subkey is part of a
composite primary key
Third Normal Form - Answers -Eliminate subkey, where the subkey is not part of the
primary key.
Recursive relationship - Answers -An association between a single class type(in one
role) and itself(in another role). An example of this would be the relationship between
managers and employee. Every Manager is an employee, but not all employees are
managers.
Aggregation - Answers -motorized vehicles ⬦ -----(1..*) parts
Composition - Answers -University ⬥ -------(1..1) Departments
Composition - Answers -Cannot exist on their own without a parent; They are created
with(or after) the parent and they are deleted if the parent is deleted.
