databases

Question 1

concept of relational databases

Answer 1

A database where separate tables are made for each entity, and
relationships between entities are represented by foreign keys.

Question 2

attribute

Answer 2

describes an entity

Question 3

composite primary key

Answer 3

A primary key made up from two or more other keys

Question 4

Foreign Key

Answer 4

attribute that joins two tables (primary key in one table and a foreign key in another)

Question 5

primary key

Answer 5

A unique identifier that identifies each record in a table.

Question 6

why a database must be normalised

Answer 6

Minimise data duplication
Eliminate data redundancy

Question 7

what does client server database system provides

Answer 7

simultaneous access to the database for multiple clients.

Question 8

how concurrent can access be controlled to preserve the integrity of the database

Answer 8

Concurrent access can result in the problem of updates being lost if two clients edit a record at the same time.

This problem can be managed by the use of record locks, serialisation, timestamp ordering, commitment ordering.