4.10 Fundamentals of Databases Flashcards
Define Data Model
An abstract model of which things to store and what information should be stored about them.
Define Attribute
A characteristic of an entity
Name the three relationship between tables in a database.
One to One
One to Many
Many to One
Many to Many
Define Entity
Something about which data can be stored
What name can be given to an attribute that can uniquely identify each attribute of a table.
Entity identifier / Primary Key
Why are databases normalised?
So that they can be at their most efficient without any compromise to the integrity of their data.
What name is given to a primary key formed from multiple different attributes?
Composite Primary Key
What name is given to the new table when forming many-to-many relationships?
Link Table
Which form of normalisation can be described as follows: All non-key attributes depend on the key, the whole key and nothing but the key
Third normal form
Which declarative language is used to query databases?
Server Query Language (SQL)
Which of the following commands would return all information from the database?
A: SELECT ALL FROM Vehicles
B: FROM Vehicles SELECT *
C: SELECT * FROM Vehicles
C
What is the role of a client server database?
To provide simultaneous access to a database for multiple clients.
What problem occurs when different users try to access the same field simultaneously?
Concurrent Access
In which form of normalisation are key dependancies removed?
Second form Normalisation
Name three ways of managing concurrent access.
- Record Locks
- Serialisation
- Timestamp ordering
- Commitment ordering
