Data Bases Flashcards
Define data model
An abstract model of which things to
store and what information about them§
should be recorded
Define attribute
A characteristic of an entity
Name the three possible degrees of relationship
between tables in a database
One-to-one
One-to-many
Many-to-many
Define entity
A thing about which data is to be stored
What name is given to an attribute which can
uniquely identify each attribute in 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 created when
forming a many-to-many relationship?
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
3NF
Which declarative language is used to query
databases?
Server query language (SQL)
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 attempt to
access the same field in a client server database
simultaneously?
Concurrent access
In which form of normalisation are partial key
dependencies removed?
Second normal form (2NF)
Name three ways of managing concurrent access
Record locks
Serialisation
Timestamp ordering
Commitment ordering
