Chapter 10

Chapter 10: Managing a Database

Database is a collection of data organised in a manner that allows access, retrieval and use of that data (collection of unprocessed items such as text, image, numbers, audio and video). Managing a database is rather important because it will affect the productivity of a company. Processed data is called information and it contains documents, audio, images and video. And luckily, there are plenty of database software a.k.a database management system (DBMS) that will help managing a database.
It allows users to:
1) Create a computerised database.
2) Add, modify and delete data.
3) Sort and retrieve data.
4) Create forms and reports from the data.

Some terms found:
1) Data integrity- identifies the quality of the data.
2) Garbage in, garbage out (GIGO)- accuracy of a computer's output depends on the accuracy of the input.

Valuable information is what every users need and it is very important for a company in its daily operation and long term decision or strategies.
Characteristics of valuable information:
1) Accurate- valuable information needs to be accurate and free from error.
2) Timely- valuable information needs to be up to date.
3) Organised- valuable information needs to be organised for easier reading.
4) Accessible- valuable information needs to be accessible for any users at any time.
5) Useful- valuable information needs to be useful in terms of its content.
6) Cost effective- valuable information needs to be cost effective that is getting high quality information at low price.

Hierarchy of data, from the top layer:
1) Character- is one byte and contain any numbers, letters, space, punctuation marks or other symbols.
2) Field- a combination of one or more related characters. Contain:
i) Field name
ii) Field size
iii) Data type such as text, numeric, auto number, currency, date, memo, yes/no, hyperlink, object and attachment.
3) Record- a group of related fields.
4) File- a set of records.

File maintenance refers to the procedure of adding, modifying and deleting records.
Validation compares data with a set of rules or values to find out if the data is correct. Database validation is required when databases get corrupted to check for corruption.
Types of validity checks:
1) Alphabetic/Numeric check- check if the alphabet or numbers are correct according to setting.
2) Range check- check that a value falls within a specific range.
3) Consistency check- check fields to ensure data in these fields corresponds.
4) Completeness check- check fields to ensure data in these fields are complete in terms of requirements.
5) Digit check- the last one or two digits are used to check the other digits are correct.

File processing versus Database approach.
File processing system:
1) Each department has its own set of files.
2) Have data redundancy.
3) Isolate data.

Database approach:
1) Programs and users share data.
2) Reduce data redundancy.
3) Improve data integrity.
4) Share data.
5) Allow easier access.
6) Reduce development time.
7) More vulnerable.

Features in database management system:
1) Data dictionary- contains data about each file in the database and each field in those lines.
2) Query language- consist of simple, english-like statements that allow users to specify the data to display, print or store.
3) Query by example (QBE)- provide a graphical user interface to assist users with retrieving data.
4) Form- window on the screen that provide areas for entering or modifying data in a database.
5) Report generator- allows users to design a report on the screen, retrieve data into the report design and then display or print the report.
6) Security- only authorised users can access data at permitted times such as access privileges and principle of least privilege.
7) Backup and restore- to save the data in database in another storage medium and can be returned to its original form later.
8) Data model- consists of rules and standards that define how the database organises data.
For example:
i) Relational database- stores data in tables that consist rows and columns. Relationship is the link within the data.
ii) Object oriented database (OODB)- stores data in objects. Examples of applications are multimedia database, groupware database, computer-aided design database and hypertext database.
iii) Object relational database- create relationship between object oriented data.
iv) Multidimensional database- can store data in more than two dimensions of data. A.k.a hypercube and it can consolidate data much faster than a relational database.
9) Data warehouse- huge database that stores and manages data required to analyse historical and current transactions.

Features of Web database:
1) Shop for products or services- Amazon, Alibaba.
2) Buy or sell stocks- NASDAQ.
3) Search for a job- Jobstreet.
4) Make airline reservations- Air Asia, Malaysia Airline, Tiger Air.
5) Register for college classes- UCSI Information Integrated System (IIS).
6) Check semester grades- UCSI IIS.

Database administration helps in the productivity, maintenance and design of database.
Guidelines for design of database:
1) Determine the purpose of the database.
2) Design the tables or files on paper first and each table or file should contain data about one subject.
3) Design the records and fields for each table or file.
4) Determine the relationships among the tables or files.
Database is managed by:
1) Database Analyst (DA)- decides on proper field placement, data relationship and identifies user's access privileges.
2) Database Administrator (DBA)- creates and maintains the data dictionary, manages security, monitors performance and checks backup and recovery procedures.