01 Database Overview Flashcards
1
Q
What is a database
A
- an organised collection of information
- can be simple records, text, excel
- can be any size
2
Q
What is a database management system DBMS
A
- professional
- standardised protocols and frameworks
- eg. mySQL - abstraction
- data to interface to user
- physical layer: how data is stored in disk
- logical: communication protocol
- view layer: user perform queries
- concurrent access
3
Q
DBMS advantages
A
- data concurrency
- data searching
- data redundancy
- data inconsistency
- data integrity
- data sharing
4
Q
stages of database design
A
- requirement analysis
- conceptual database design
- logical database design
- refine schemas
- physical database design
- application and security design
5
Q
requirement analysis
A
- bidirectional
- clients tell what they want
- what data to store
- what kind of application
- what operations are needed
6
Q
conceptual database design
A
- given user requirements, create ER diagrams
2. create relations for all entities
7
Q
logical database design
A
- determine DBMS
- finalise ER diagrams
- decide on columns and rows
8
Q
schema refinement
A
- analyse relations
- identify potential problems
- refine
- normalisation: reduce data redundancy and improve integrity
9
Q
physical database design
A
- further refinement
- ensure meets performance criteria
- build index on tables, cluster tables
10
Q
application and security design
A
- identify what is accessible/ inaccessible
2. enforce rules
11
Q
Data model main components
A
- data
- relationship
- constraints
12
Q
what is a super key
A
primary key + candidate key
13
Q
what is a candidate key
A
potential primary keys
14
Q
what are integrity constraints
A
database is legal if ICS holds for all data
eg. reject insertion of student with non existent student ID
