1. ITGS
Databases

2. Databases Databases - organized collections of related data Databases
Databases are at the heart of many IT systems
Example: student records
Databases
Data is stored in an organized manner so that it can be retrieved later
Business databases , transport databases
Search engines - (I.e. Google) use databases to store both the contents of web pages (to enable their searches to work) and details about user’s behavior, including common searches and topics of interest

3. DBMS Database Management Systems (DBMS)
Online databases (Wikipedia) - hold huge volumes sof articles, images and video accessible to anyone with an Internet connection
Government databases
Database Management Systems (DBMS)
The software used to create and maintain databases
Spreadsheet applications like Microsoft Excel focus on numerical calculation and are not considered database programs
Database structure - organizing information into fields, records, and tables, determined by how the pieces of data relate to eachother

4. Database Structure
Fields - smallest pieces of information in a database
A property of an item
Record - collection of fields that relate to the same item
Table - collections of records that are all the same type
Primary key, or key field - a field which is different for every record in that table, allowing each record to be uniquely identified

5. Structure of keys
Composite key - using two separate fields together to form a composite key
separately they do not uniquely identify records, but they do when combined
Secondary key or alternative key or index - a field which might frequently be used to search a table.
This key doesn’t have to be unique; a table can have several secondary keys
Data type - determines what sort of data can be stored in each field in a database - text, numbers, a date or an image

6. Flat File Databases
Data types are a good first step to helping ensure alidation of data by allowing only data of the desired type
Flat file databases - a database which contains just one table
Adequate for storing small amounts of simple data
Redundant data - data that is needlessly repeated
Redundant data causes several problems:
Data integrity
The more often data is repeated, the higher the chance that a mistake will be made

7. Relational Database Relationships
Relational database - splits data into multiple tables, each containing records related to one type of item or entity
Normalization - creating a relational database which has no redundant data
Relationships
Once the data has been normalized into separate tables, those tables must be linked, or related, to other tables
This way, the details can be referenced from one table to another
One-to-many relationship
for example, one author has many books, but each book has only one author
Foreign key
A field which exists to be part of a relationship with another table

8. Queries
Query - a way of selecting only the records in a database that match certain criteria
Queries are essential for accessing only the required information from a database
Boolean operators - mathematical operators such as greater than or less than to compare values, such as AND, OR, and NOT are used to combine criteria in a search
Parameter queries
Prompt the user for a value when the query is run
The data entered by the user is used as the criteria for the field
Forms
Used to present a user friendly graphical interface for entering and altering data in a database
Forms shield users from the complexity of database tables, queries and relationships

9. CSV and TSV
CSV and TSV are common ways of transferring data between different database and spreadsheet applications
Useful when programs use different file formats to store their data
Both save fields and records into plain text files, which can be read by most database and spreadsheet programs
Also referred to as comma or tab delimited values
CSV (comma separated values) - separate each field value with a comma
TSV (Tab Separated Values) - separate each value with a tab
Reports
A way of presenting data from a table in a database in a more professional manner than the default data sheet view
Report layouts can be customized
Color, data field layout, etc.
Structured Query Language
SQL - a language for writing instructions to manage databases

10. SQL Issues: Integrity Validation
Designed to be easily understandable by humans
Compatible across different database products
Can be used to create fields, records, tables, run queries, and edit or delete information
Issues: Integrity
Data integrity - ensuring that data is correct, relevant and up to date - one of the biggest issues related to databases
Validation
The process of ensuring that data is in the correct format for a particular field
For example: when a credit card number is entered, it shoul contain exactly 16 numbers
Just ensures correct format, not correct data
Microsoft Access - input mask allows the user to specify requirements for each character of the input

11. Verification Verification - checks that data is actually correct
Very hard to achieve
Several possible techniques:
Entering data twice
People enter data once, then enter it again, and the system highlights any differences between the two sets of data and requires resolution
Comparing with the original documents - comparing the original paper with the data entered
Verifying with the data subject - asking someone if the data is correct
Issues: Privacy
Data warehouses and centralized databases have allowed vast amounts of data to be collected, stored and processed
Data matching - used to build up a profile of an individual by combining data bout them from several databases
Data mining - discovering hidden patterns and trends in large databases

12. Privacy The UK has a really large DNA database
UK Data Protection Act specifies how companies can collect, store and use personal data:
Obtain consent
State purpose of collection
Distribution to 3rd parties (disclosure)
Length of storage (destroy when no longer needed)
Security

13. Security
Database auditing - allows data controllers to view both successful and unsuccessful attempts to access, change or delete data in a database