Database

Question 1

Data integrity

Answer 1

Entity integrity: each set of data must be uniquely identified

Domain integrity: each field should adhere to the same format and definition

Referential Integrity: Foreign keys should point to existing primary key values

Question 2

Data Redundancy

Answer 2

Situation where an identical field is repeated in two or more records

Can potentially lead to data anomalies and corruption and hence should be avoided

Question 3

Data Dependency

Answer 3

Where data in different tables are related to each other

Occurs when one of the fields in the table leads the system to another table so that more information may be extracted from the same set of data

Question 4

SQL vs NoSQL

Answer 4

Structured vs Unstructured
Strict vs Flexible
Scales up vs Scales out

Question 5

Structured vs Unstructured

Answer 5

each field has a fixed data type
each record has the same fields

vs

not

Question 6

Strict vs Flexible

Answer 6

Schema is difficult to change (due to defined constraints)
Maintains strict data integrity

vs

Allows hierarchical data storage (differentiating between fast and slow storage devices)

Question 7

Scales up vs Scales out

Answer 7

Difficult to check constraints across multiple servers
Needs more powerful machine

vs

Collection can be split across multiple servers