1. List, describe, and provide an example of each of the five characteristics of high quality information.
Accuracy- Are all the values correct? E.g. named spelled correctly? Dollar amount recorded properly?
Completeness- Are any of the values missing? E.g. is address complete including state, street, city state and postcode?
Consistency- Is aggregate or summary information in agreement with detailed information? E.g. Do all total fields equal the true total of individual fields?
Uniqueness- Is each transaction, entity and event represented only once in the information? E.g. are there any duplicate customers?
Timeliness- Is the information current with respect to the business requirements? E.g. is information updated weekly, daily or hourly?
2. Define the relationship between a database and a database management system.
Whatis.com defines a database as: "a collection of information that is organised so that it can easily be accessed, managed, and updated. In one view, databases can be classified according to types of content: bibliographic, full-text, numeric, and images." (http://searchsqlserver.techtarget.com/definition/database).
A database is the heart of an organisation. It is a structured collection of related data e.g. a filing cabinet, an address book, a telephone directory, a timetable, etc. It stores key business information like;
* Sales Data – customers, sales, contacts.
* Inventory Data – orders, stock, delivery.
* Student Data – names, addresses, grades.
All businesses use a database of some type. Effective managers know the value of extracting of important data.
A Database Management System (DBMS)- provides all users with access to all the data. It’s software through which users and application programs interact with a database. For examples they can produce reports, run queries through programs such as access (a collection of related tables).
Wisegeek.com explains that a dbms is a computer software program that is designed as the means of managing all databases that are currently installed on a system hard drive or network. Different types of database management systems exist, with some of them designed for the oversight and proper control of databases that are configured for specific purposes. (http://www.wisegeek.com/what-is-dbms.htm)
3. Describe the advantages an organisation can gain by using a database.
DBMSs provide many advantages for an organisation as they minimise the following problems:
- Data redundancy: The same data is stored in many places.
- Data isolation: Applications cannot access data associated with other applications.
- Data inconsistency: Various copies of the data do not agree.
Databases also ensure that:
* Data security is maintained: Through keeping the organisation’s data safe from theft, modification, and/or destruction.
* There is a high level of data integrity: Data must meet constraints (e.g. student grade point averages cannot be negative).
* Data independence exists: Applications and data are independent of one another. Applications and data are not linked to each other, meaning that applications are able to access the same data.
High quality information can significantly improve the chances of making a good decision and directly increase an organisation’s bottom line.
INCREASED FLEXIBILITY- A good database can handle changes quickly and easily. Each user can access information in own way. Physical view> physical storage of information e.g. hard disk. Logical view> focuses on how users seek information to best suit their needs.
INCREASED SCALABILITY & PERFORMANCE- Databases scales to handle masses of information. How well a system can adapt to the increase in demands.
REDUCED INFORMATION REDUNDANCY- the duplication of information, or storing the same information in multiple places. It occurs because organisations frequently capture and store the same information in multiple locations. The problem is that it can often be inconsistent. Eliminating information redundancy saves space, makes performing information updates easier and improves information quality.
INCREASED INFORMATION INTEGRITY (QUALITY)- Measure of the quality of information. Integrity constraints are rules that help ensure the quality of information. They can be defined and built into the database design.
2 types of integrity constraints: relational (rules that enforce basic and fundamental information-based constraints) and business-critical (enforce business rules vital to an organisation’s success and often require more insight and knowledge then relational integrity constraints).
INCREASED INFORMATION SECURITY- Organisation must protect its information from unauthorised users or misuse. Therefore, databases offer passwords, access levels and controls.
4. Define the fundamental concepts of the relational database model.
* A relational database is a collection of tables from which data can be accessed in many different ways without having to reorganise the database tables. It stores information in logical 2D tables that relate to each other.
* Once these relationships are created, we can create links that relate the tables to find:
- Which students are attending all tutorials.
- Which students have high distinctions.
- Which subject has the highest failure rate.
- An example of the model can be seen below:
http://www.blurtit.com/var/question/q/q1/q19/q192/q1922/q192204_414325_673px-er_diagram_mmorpg.png
5. Describe the benefits of a data-driven website.
* Development- allows website owner to make changes any time. All without having to rely on a developer knowing HTML programing.
* Content management- a static website requires a programmer to make updates. This adds an unnecessary layer between the business and its web content which can lead to misunderstandings.
* Future expandability- having a data-driven website enables the site to grow faster than would be possible with a static site. Changing the layout, displays and functionality of the site is easier with a data-driven solution.
* Minimising human error- a well designed, data-driven website will have ‘error-trapping’ mechanisms to ensure that required information is filled out correctly and that content is entered and displayed in its correct format.
* Cutting production and update costs- Can be updated and published by any competent data-entry or administrative person. It is convenient and affordable and changes and updates take a fraction of the time of static sites. Training a data-entry person can be done in up to an hour.
* More efficient- The system keeps track of the templates so users do not have to. Layouts and structures only have to be programmed once. It improves the reliability and stability of a website, while reducing the chance of ‘breaking’ some part of the site when adding new areas.
* Improved stability- There is a peace of mind knowing the content is never lost- even if your programmer is.
6. Describe the roles and purposes of data warehouses and data marts in an organisation.
The role of a data warehouse is to logically collect information, gathered from many different operational databases, that will support business analysis activities and decision-making tasks.
The primary purpose of a data warehouse is to aggregate information throughout an organisation into a single repository for decision-making purposes.
A data mart contains a subset of data warehouse information. Its role involves allowing organisations to run transactional data and visibility upon the whole organisational whilst showing the relationship between the sectors.
Tech target defines a data mart’s role as being “designed to serve a particular community of knowledge workers. In scope, the data may derive from an enterprise-wide database or data warehouse or be more specialized. The emphasis of a data mart is on meeting the specific demands of a particular group of knowledge users in terms of analysis, content, presentation, and ease-of-use. Users of a data mart can expect to have data presented in terms that are familiar.” http://searchsqlserver.techtarget.com/definition/data-mart
In a data warehouse and data mart, information is multi-dimensional; a cube, it contains layers of columns and rows. Data warehouses have a more organisational focus whereas data marts have focused information subsets (a part of a larger group of related things) particular to the needs of a given business unit e.g. finance.
No comments:
Post a Comment