Unit 7: Store and Retrieve it

Database Management Systems (DBMS)

Social and ethical issues

Evaluate the social and ethical issues involved in the use of databases and spreadsheets. These may include:• privacy of information in different cultures

• responsibility for the security of data stored in databases from different perspectives, for example, the developer, the user and the management of an organization

• accountability for the negative social effects caused by insecure databases

• rights of individuals with respect to the storage of personal data

• social consequences of outdated or incorrect data stored in databases

• social consequences of the release of sensitive data stored in databases

• legislation on access and use of database information in different countries

What Is A Database?

• A Database is simply a collection of data

– A list of Names and Addresses– CD’s in your Personal Collection– Customers details, products, orders

These days Databases are often referred to data held on computer but non-computerized databases still exist is

such circumstances where the amount of data needed to be held is not so large such as a small primary school may

hold pupils data on an index card

Difference Between Computerized and non-computerized Databases

Computerized Faster Access to data Data Which usually takes a

weeks, months to collate takes minutes

Search data faster Able to analyse data in ways

that were previously unthinkable. Buying habits of customers.

Non-Computerized Low maintenance required Filing system does not crash

Key Database Terms• A Database

– A collection of data stored in an organised way.

• A table– Where to enter data.– Where the data is stored

• A Record– One set of information on a person or thing.

• A field– One specific piece of information on a person or thing.

More Terms• A Query

– Extracting a specific subset of data (Searching for data)

• A Form

– a way to enter data into a table– a way to view data from a table or query

• A Report

– A way to print out data from a table or query.Example Database

Are these the same?

MS Access Database Table

MS Excel Spreadsheet

What’s the difference between a Database and a Spreadsheet?

The difference….relations• A relational database is a database that groups data using common attributes

found in the data set. The resulting "clumps" of organized data are much easier for people to understand.

• For example, a data set containing all the real estate transactions in a town can be grouped by the year the transaction occurred; or it can be grouped by the sale price of the transaction; or it can be grouped by the buyer's last name; and so on.

WikiPedia

Data Reliability

• “Data may be unreliable if it is entered incorrectly or if it becomes outdated”• Ways to prevent data entry errors include:

• Field types i.e. only a certain type of data is permitted e.g. only text• Limiting field size eg Title 25 characters• Default values to input the most likely field value• Validation rules to ensure values within a given range eg cost >10 and <100• required fields so null values are not allowed• drop down boxes to limit the data entry choice

eg Videos– Shelf default value – Latest Releases– Rating validation rule - "G" Or "PG" Or "M" Or "MA" Or "R"– Fee default value – 6– Fee validation rule - >=2 And <=6– Time_Limit validation rule - >=1 And <=7

Data Redundancy

Definition: Repetition of data in a database

Why do you think this could cause problems?

Database Integrity

• Integrity refers to the data staying the same as when it was entered at creation. Data can lose

• integrity if it is changed by a hacker or if it is destroyed during transfer eg over a communications network.

Data Matching• “Data-matching involves bringing together data from different sources and

comparing it.

• Much of the data-matching done by agencies subject to the Privacy Act aims to identify people for further action or investigation. For example, records from different departments are often compared to identify people who are being paid benefits to which they are not entitled or people who are not paying the right amount of tax.

• Data-matching poses a particular threat to personal privacy because it involves analysing information about large numbers of people without prior cause for suspicion”.

• (Office of the Federal Privacy Commissioner http://www.privacy.gov.au/act/datamatching/)

Data Mining“A class of database applications that look for hidden patterns in a group of data that can be used

to predict future behaviour”

For example, data mining software can help retail companies find customers with common interests.

• The term is commonly misused to describe software that presents data in new ways. True data mining software doesn't just change the presentation, but actually discovers previously unknown relationships among the data.

• Data mining is popular in the science and mathematical fields but also is utilized increasingly by marketers trying to distil useful consumer data from Web sites”

• “Data mining is the discovery and extraction of hidden predictive information from large databases. It uses statistical methods and artificial intelligence technology to locate trends and patterns in data that would have been overlooked by normal database queries. For example, a grocery chain used data mining to discover differences between male and female shopping patterns so they could create gender-specific marketing campaigns”.