Primary Key
a field which uniquely identifies a record in a database
Foreign Key
A primary key rom one table included in another table to form linke between them
Flat File Database
May contain a number of single tables with no links between them
Data Redundancy
The storing of the same data more than once
Loss of Data Consistency
- Data is stored more than once
- Not all instances of data will be updated is a change is made
Relational Database Advantages
- Reduces redundancy
- Data consistency
- Data independence
- Allows different views of the same data
- Allows easy extension to the structure of the database
Relational Database Disadvantages
- Data complexity - when data resides in multiple tables which are linked to each other through shared key values
- Maintaining or modifying relational databases can be difficult
- Broken keys and records producing errors in other tables
Database Management System
- Stores data accessed by multiple types of user
- Different users may have different access rights
- Different users may have different levels of access to different data sets
- Access is password protected
Tasks Carried out by IT staff on a DBMS
- Setting up tables, queries and reports for different classes of user
- Maintenance and performance management
- Allocating usernames and passwords
- Making backups and disaster recovery
- monitoring access/audit logs
- Maintiain security
- Encrypt confidential data
- Update hardware/software as necessary
- Provide help desk service
- Provide Training
Data Dictionaries
Database ‘metadata’ - defines how the database is structured, the users and their access rights
Big Data
Data with volume, variety and velocity.
- Very large data sets
- Very complex, unstructured data- mixture of media
- New data generated rapidly and traditional databases are unable to manage and process this media within acceptable time frames
Data Warehousing
where large quantities of data are collectted together from a variety of locations for effiecient analysis
Data Mining
The retrieval and analysis of large sets of data in a data warehouse to identify trends and patterns
Predictive Analytics
A sub set of data mining used to make predictions about future events based on individual historical behaviour.
Consisits of variety of statistical techniques including modelling, machine learning and data mining
