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留学作业网专业指导英国ASSIGNMENT。Managing data resources and Databases
Learning outcomes
Be able to use the appropriate terminology to explain the elements in a database
Understand what is meant by the database approach and explain why it is important to organizations
Be able to explain the concepts of database design and relational databases
Appreciate the elements of the management of databases in organizations
Why databases?
Databases are the core of all information systems in all businesses
All organisations collect data, and use this to keep records of the transactions that they perform with suppliers and customers.
Each department or function within a business maintains a database that supports its specific activities e.g.
Finance departments - record financial transactions
Marketing departments – record sales, and customer details
Many managers are involved in specifying their content and methods of reporting information
An understanding of databases assists managers to appreciate how data and information can be captured, stored, retrieved and manipulated in organisations.
Definitions of ‘database’
Simple database definition: a collection of data organized by database software, so that it can be stored and retrieved.
Databases with multiple files:
Simple definition: a group of related files
Rigorous definition : a collection of data organized to service many applications at the same time by storing and managing data so that they appear to be in one location
More on databases
A database management system (DBMS) is a system that generates, runs and maintains databases, and as a such the system must include all of the software needed for this purposes
Databases are designed (or structured) (database design) so that the data in them can be used for a variety of different purposes.
Data can be selected from databases (using queries) to be presented in on-screen or printed reports.
Data is entered into, or edited in databases using on-screen input forms.
More definitions
Field – the basic element in that database
Record – a group of related fields
File or table – a group of records of the same type
Database – a group of related fields or tables
Entity – a person, place, thing or event about which information must be kept
Attribute – a piece of data describing an entity
Key field – a field in a record that uniquely identifies instances of that record so that it can be retrieved, updated, or sorted.
Databases : field types
Number
Currency
Text
Yes/No
Date/Time
Take a look at Access and discover that there are different formats for a number of these field types.#p#分页标题#e#
Think Point: Why do we need to specify the data type???
Number
Currency
Text
Yes/No
Date/Time
Take a look at Access and discover that there are different formats for a number of these field types.
Think Point: Why do we need to specify the data type???
Validation is about checking user entries
Mandatory
Data type
Range check
Restricted list
From the File Approach to the Database Management Approach
Early business IT systems were developed to solve specific problems, so each functional area developed systems in isolation from other areas.
This led to lots of files across the organization – some with similar but slightly different data in them. More specifically the problems were:
Data redundancy – duplicate data in multiple files
Program data dependence – in which any change in the data in the files required a change in the software supporting the storage of those files.
Lack of flexibility and difficulties in responding to ad hoc requests
Poor security – due to limited control of the updating of, and access to data
Lack of data sharing and availability – data scattered across files
Advantages of the Database approach
Multi-user access
Distributed access
Speed
Data quality
Security
Space efficiency
Example of the Database Approach
Integrated Human Resources Database
Employees
Name
Address
Social security number
Position
Marital status
Payroll
Hours worked
Pay rate
Gross pay
Tax
Net pay
Benefits
Life insurance
Pension plan
Healthcare plan
Database Management Systems
Database Management Systems (DBMS) are the software that permits an organization to centralize data, manage them efficiently, and provide access to the stored data by application programs.
http://www.ukassignment.org/daixieAssignment/daixieyingguoassignment/Microsoft Access is a simple DBMS for desktop systems – Other include ORACLE Database, DB2 and Microsoft SQL.
DBMS separate the physical and logical view of the data:
Logical view – a representation of the data as they would appear to an application programmer or user
Physical view – the representation of the data as they would actually be organized on physical storage media
Databases : Logical Design
There are a number of different types of databases, including:
Relational
Hierarchical and Network, and
Object Oriented
Relational databases – are the most common. These have a database structure in which data is held in a number of tables, each of which has a primary key to link it to other tables.
Databases are broken down into tables of related grouped data to minimize data redundancy (wasting space) and maximize speed and reporting capabilities#p#分页标题#e#
An Example of a Relational Database
Note the common fields – these can be used to link tables together – called primary keys – allow data to be used on the same document (report) from several tables. The process of designing such data structures is called normalisation
Object-Oriented Databases
Popular in web environments
Relational DBMS organize data into rows and columns – this approach is less suitable for databases of drawings, images, photographs, voice, and video.
Object oriented databases and Object oriented database management systems (OODBMS) handle multi-media components (java applets) more effectively – and store more complex prices of info.
Information is stored at objects, and procedures are defined for manipulating objects, so that the objects can be retrieved and shared.
Databases : Stages in creation
1 Identify entities and fields (design)
2 Create table structure - which fields in each table (using ‘design’ view in Access)
3 Enter data to ‘populate’ each table (using ‘open’ view in Access)
4 Setup and run queries for reporting and decision making
It is not sufficient to design a database system, it also needs to be managed. The elements of this management are:
Data administration-
the function with the power to define the information requirements for the whole organisation. This involves developing information policy, planning for data for new activities, overseeing logical database design, data dictionary development, and monitoring how data is used.
The underpinning principle is that data are the property of the organization
Information policies specify the rules for sharing, using, accessing disseminating ,acquiring, standardising, classifying and storing information throughout the organization
Database administration-
The more technical and operational aspects of managing data, including physical database design and maintenance
Data planning and modelling methodology
Enterprise analysis identifies the key entities, attributes and relationships that constitute the organization's data.
This must take an organization wide perspective.
Users
User interaction with the database must be supported, through:
Ongoing input to database design
Training and help facilities
Organisations are using the Web to allow customers and business partners to:
See the data in their database e.g. product database
留学作业网专业指导英国ASSIGNMENT。Input data – e.g. order or user registration (through database forms)
This is useful because:
People know how to use web browser software – hence need less training
Web interface requires few if any changes to internal database – important with large legacy databases#p#分页标题#e#
How it works….
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