Docstoc

Assignment Database

Document Sample
Assignment Database Powered By Docstoc
					ASSIGNMENT DATABASE 2009

Table of Content
Bil 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Indices Definition of Database Database Example Advantages of Database Database Models Database Suggestion Database Suggestion (Model) Differentiations of File-Based and Database Definition of Database Management System (DBMS) Components of Database Management System (DBMS) Facilities of Database Management System (DBMS) Functions of Database Management System (DBMS) Roles in Database Environments Advantages of Database Management System (DBMS) Example of Database Management System (DBMS) Problems of File-Based on Developing Staff Information System Roles of Database Administrator in Developing Staff Information System Page 3 4 6 12 15 16 17 18 19 21 22 26 28 35 37 38

1

Definition of Database
In computing language, database is definite as a collection of logically related data that being shared, and description of this data was designed to meet the information needs of an organization. The database is a single, possibly large repository of data that can be used concurrently or simultaneously by many department and users. For example:-

Doctorial Department

Patients Diseases Drugs

Patients Registration Unit

Pharmaceuticals Department Diagram: Database can be shared corporate resource. All data items are integrated with a minimum amount of duplication. The database not longer own by one unit or department in one organization but it is shared corporate resource. The databases hold not only the organization’s operational data but also a description of this data. That’s why a database is also defined as a selfdescribing collection of integrated records. Example at the company, all managers can access the staff information by using department’s computer to know information about the staff at the company. They no need to open each of files to get the information. The managers only need to key in the statement needed and the database will search it for them.

2

Database Example
Nowadays, we do not aware the usage of databases in our daily life eventhough it is now such an internal part of our day-to-day life. One example of databases that we used daily is involved of Staff Information System. The example stated was based on the scenario given. For ITtoYou Sdn. Bhd, Staff Information System is needed for company management in certain department. Each of local departments may need the information about staff name, staff salary, staff expertise, staff qualification and so on. The database will be a computerized index that allows user to find the staff information based on his/her qualification or its name. Other process is maintains and updates staff information. It can maintain the staff name and qualification within a security system that allowed certain users or departments to modify it. So, the information will be secured and cannot be interrupted by any user. The example was about on how the database being linked and operate. The first database was about STAFF table which contain Staff ID, Name, I/C, Gender, and Qualification. The STAFF table was linked to the WOTK table by using Staff ID as a reference. In WORK table, the attributes consist of Ex Id and Work. Then the WORK table is linked to WORK DEPARTMENT table by Ex ID from the WORK table. In WORK DEPARTMENT table there is another references which from DEPARTMENT table. The reference is Dept ID. Besides that, another attribute in WORK DEPARTMENT table is WID. Another attribute in last table which known as DEPARTMENT table is title. The example is stated in the next page.

3

Staff ID ITD 209 ITD 210 ITD 211 ITD 212

STAFF Name I/C Gender Qualification Saiful Azham 830921-14-8923 Male BA(Hons) Lee Chaolan 711211-06-7845 Male Degree Nai Ruby 810812-45-8888 Female BA (Hons) William Juide 810231-45-7683 Male Degree

Ex ID EXP 08 EXP 09 EXP 10 EXP 11

WORK Work Accountant Network Engineer Computer Maintainer Sales Manager

Staff ID ITD 210 ITD 211 ITD 209 ITD 212

WORK DEPARTMENT WID Ex ID Dept ID EXP DMN WD11 08 08 EXP DMN WD12 09 09 EXP DMN WD13 10 09 EXP DMN WD14 11 10

DEPARTMENT Dept ID Title DMN 08 Accounting DMN 09 Computer & Networking DMN 10 Production

4

Advantages of Database
Database consist a lot of advantages that become one of reason why we use database:1. Less Duplication of Data
Using database is better than using the file-based which is less duplication of data will be occurred. What is mean by less duplication of data? The data will not be redundant or being copied several times when we want to modify it. We just modify the data or information needed in one update and stored in one place only. When the user wants to update the address of the staff for example, he/she just need to change it in one file. Rather when using file-based, user needs to change the data from each file.

As example, we modify the word “Hamsah” to “Hamzah”

Automatically the data in other file will change. This shows that less duplication of data in database.

5

2. Integrated Data
While using database, all application data is stored in single facilities. Data maybe redundant but in other files not in same files, which means there’s no same data in one file. For example, if there has two name of Ong Hao Kent in one file but other data about them is difference like address or state, the data is acceptable. In the other hand, if the data is same in one file there maybe will be a conflict on it.

In diagram show above, the staff may same but other information of the staff are different.

If the data are being duplicated, this message will appear to show that the data maybe conflicted.

Rather than when using file base, user cannot trace the data that have being redundant and there is no data integrated in file. This lackness may conflict the data information.

6

3. Efficient Data Access
Database make the data managing more efficient on it access. The data is variety of technique to retrieve, store and update. User no need to scroll down the file to search the data needed like file-based system. User just needs to state the statement needed and the data will appear. For example, if user need to change the address information in data about staff that work on ITtoYou Sdn. Bhd, he/she just key-in the statement needed and changed it.

As example, we modify the word “Hamsah” to “Hamzah”

7

4. Data Independence
Database advantage of data independence is meant by techniques that allow data to be changed without affecting the applications that process it. Data independence which is accomplished in a Database Management System (DBMS) allows the database to be structurally changed without affecting most existing programs. It is because DBMS provide an abstract view of data to insulate application code from details. Programs access data in a DBMS by field and are concerned with only the data fields they use, not the format of the complete record. Thus, when the record layout is updated (fields added, deleted or changed in size), the only programs that must be changed are those that use those new fields. For example, when the manager of ITtoYou. Sdn. Bhd wants to change the staff department record. He/she will only change the data without changing the data format of the database.

Examples above show that the data application does not change eventhough the data have been changed. 8

5. Easier of Representing Data in User’s View
Database in Database Management System (DBMS) have a relationship among data which represented DBMS utility. This relationship of data or data integration may help user to search the data by filtering the features of data needed. Rather than file-based system, the data maybe quite difficult to be found because user needs to sort each data in order to find the data needed. As example, when a department or unit in ITtoYou. Sdn. Bhd wants to know just only the staff department, they just choose the department title and the information and the data about the department will appeared.

9

6. Concurrent Access and Crash Recovery
What is mean by concurrent access? Concurrent access meant a lot of users use the database at the same time but schedules concurrent access thinks one user at a time. Therefore user can use the database simultaneously without any problem rather than the usage of file-based which user can use the file at the same time but the right to access or change the data is blocked by read-only term. For example, when Finance Department and Human Resource Department in ITtoYou Sdn. Bhd Company want to access the staff information system concurrently, Database Management System (DBMS) will allow both of them to access and use its database’s. While crash recovery is a system that prevent database from data lost. The data will backup manually or automatically to prevent from the data lost when the database is being attacked by virus or by the unauthorized user especially. For example, when staff information system in ITtoYou Sdn. Bhd had being attacked by a hacker, their data maybe lost or corrupted. The advantage of crash recovery will restored previous well backup data to operate the system backed.

10

Database Models
There are three types of most common models use today in database. The three of databases are:1. Hierarchical Model
Various techniques are used to model data structure. Most databases are built around one particular data model. For example hierarchical model which is data is organized in tree structure, implying a single upward link in each record to describe the nesting, and a sort field to keep the records in a particular order in each same-level list. Data in a series of record, which have a set of field values attached to it. There is a hierarchy of parent and child data segments. The Parent Child Relationship is one to many (1: M). The hierarchical model is a restricted type of network model. Again data is represented as collection of records and relationships are represented by sets. However, this model allows a node to have only one parent. Recordbase (logical) data models are used to specify the overall structure of the database and a higher-level description of the implementation. Their main drawback lies in the fact that they do not provide adequate facilities for explicitly specifying constrains on the data, whereas the object-based data models lack the means of logical structure specification but provide more semantic substance by allowing the user to specify constrains on the data. Hierarchical model was firstly represented by Rockwell & IBM in year 1968. The model which was implemented primarily by IBM's Information Management System (IMS) only allows one-to-one or one-to-many relationships between entities. However some IMS also provides nonhierarchical features. The example show in the next page, show the example of hierarchical model of Staff Information System in ITtoYou. Sdn. Bhd

MINISTRY OF FINANCE

MINISTRY

BUDGET

BSKL

PROJECT

MINISTER

PTD

CABINET

11

2. Network Model
In the network model, data is represented by sets of records, and relationship represented by sets. In this network, some data were more naturally modelled with more than one parent per child. Network data model also permitted the modelling of many-to-many relationship in data. Any record can be related to any number of other elements. The usage of this model is very slow and difficult besides than wasting the time. In 1971, the Conference on Data Systems Languages (CODASYL) formally defined the network model. The basic data modelling construct in the network model is the set construct. A set consists of an owner record type, a set name, and a member record type. Popularity of this network was coincided within the popularity of hierarchical model. The data model is a simple network, and link and intersection record types (called junction records by IDMS) may exist, as well as sets between them. Thus, the complete network of relationships is represented by several pair wise sets; in each set some (one) record type is owner (at the tail of the network arrow) and one or more record types are members (at the head of the relationship arrow). Example of network model:-

FIRE DEPARTMENT

RESCUE DEPARTEMNT

TRAGEDY CONDITION

NATURAL DISASTER CONDITION

ACCIDENT

FLOOD

LAND SLIDE

12

3. Relational Model
Relational model is meaning all serious implementation of the relational model allow the creation of indexes which provide fast access to rows in a table if values of certain column are known. This model had been presented within a paper of research in 1970 by EF. Codd. Relational model is based on the concept of mathematical relations. In this model, data and relationship are represented as tables, each of which has a number of columns with a unique name. It also can link data elements from various tables provide information to users. Besides that, the sequence of column is insignificant. A relational database has no predetermined relationship between the data such as one-to-many sets or one-to-one. The basic data structure of the relational model is the table, where information about particular entity is represented in column and rows (also called tuples). Thus, the “relation” in relational database refers to the various tables in database; a relation is a set of tuples. The columns enumerate the various attributes of the entity, and arrow is an actual instance of the entity that is represented by the relation. As a result, each tuple of the employee table represent various attributes of a single employee. All relations in a relational table database have to adhere to some basic rules to qualify as relations. First, the ordering of column is immaterial in a table. Second, there cannot be identical tuples or row in table. And third, each tuples will contain a single value for each of it attributes. Tables can also have a designated singe attribute or a set of attributes that can act as a “key”, which can be used to uniquely identify each tuple in the table. Example of relational data model: DEPARTMENT FILE Dept Code IRD 186-G2 IRD 187-G2 Unit Computer Finance Venue Block B Admin Block

SUBORDINATES FILE

SubID ITR 180-21

Name William Abdullah Kamenashi Nahara

Dept Code IRD 186-G2

ITR1 180-22

IRD 186-G2

13

Database Suggestion
Scenario given was about ITtoYOU Sdn.Bhd which planning to use database systems to manage their staff information system. As a Database Administrator I prefer to use database relational model for the Staff Information System. This is because relational model use table to make file rather than other model. Besides that it is easier to use, to find the information and the data and it relation s between them are organized by table. For more information, relational model was first proposed by E.F Codd in his seminal paper ‘A relational model of data for large shared data banks’ (Codd, 1970). This paper now generally accepted as a landmark in database system, although a set-oriented model had been proposed previously (Child, 1968). Furthermore, relational model have wide capability on all aspect. One of the capability is relational model can link data elements of record in table contains the same fields. It also can link data elements from various tables provide information to users. Each row in relational model is unique and each column has unique name. Beside that, the sequence of column is insignificant. Many information systems are too complicated to be modelled as a hierarchical model. In these cases, relational models may be more practical rather than hierarchical model and network model. Only relational model can support one-to-many and one-to-one relationship because hierarchical and network just support one-to-many and many-to-many relationship. By using relational model, the user of the system can make their work more efficiently and minimize the waste of time that use for search the data and the data is redundancy. As example, managers in ITtoYOU Sdn. Bhd can easily access the information about each of their staff. They no need to search one by one file to search or update their student information. Besides that, by search one file we can know the data have in another files because data is redundancy. Moreover, relational model is easy to maintain than other model because in network and hierarchical model, data not have in one file but relational model have one key to define another files because data is redundancy with another file. Also relational model is simpler to navigate and inability to handle queries efficiently different portions of a transaction are stored in different database, more work is required to gather the data if query is performed. Relational model do not usually suffer from the referential integrity problems that occur in hierarchical database model. That’s all about the capability of relational model that suitable to use in staff information system for ITtoYOU Sdn. Bhd.

14

Database Suggestion (Model)
Staff ID ITD 209 ITD 210 ITD 211 ITD 212 STAFF Name I/C Gender Qualification Saiful Azham 830921-14-8923 Male BA(Hons) Lee Chaolan 711211-06-7845 Male Degree Nai Ruby 810812-45-8888 Female BA (Hons) William Juide 810231-45-7683 Male Degree

Ex ID EXP 08 EXP 09 EXP 10 EXP 11

WORK Work Accountant Network Engineer Computer Maintainer Sales Manager

Staff ID ITD 210 ITD 211 ITD 209 ITD 212

WORK DEPARTMENT WID Ex ID Dept ID EXP DMN WD11 08 08 EXP DMN WD12 09 09 EXP DMN WD13 10 09 EXP DMN WD14 11 10

DEPARTMENT Dept ID Title DMN 08 Accounting DMN 09 Computer & Networking DMN 10 Production

15

Differentiations of File-Based and Database
1. Data Integrated
In traditional file based, data is isolated in separate files; it is more difficult to access data that should be available. The application developer must synchronize the processing of two files to ensure the correct data is extracted. But in database is integrated data, all data is stored in single facility.

2. Data Duplication
Second is duplication of data, owing to the decentralized approach taken by each department. Duplication is wasteful, costs time and money to enter the data more than once. It takes up additional storage space and perhaps more importantly, duplication can lead to loss of data integrity. In database is less duplication of data, when data is modifying only one update is necessary.

3. Data Dependence
Next is data dependence, the physical structure and storage of the data files and records are defined in the application code. In database is data independence, DBMS provides an abstract view of data to insulate application code from details.

4. File/Data Formats
Incompatible file formats, the structure of files is embedded in the application programs, and the structures are dependent on the application programming language. The direct incompatibility of such files makes them difficult to process jointly. In database is easier of representing data in user’s view. The relationship among data represented DBMS utility.

5. Data Efficient
Finally are fixed queries or proliferation of application programs, it proved to be a great improvement over manual systems. The requirement for new or modified queries grew. There is no provision for security or integrity and in the event of a hardware or software failure was limited or non-existent. In database is efficient data, it variety of technique to store and retrieve data efficiently.

16

Definition of Database Management System (DBMS)
Database Management System (DBMS) is definite as a program or software system that have facilitate and enables one or more computer users to define, create, maintain and control access data in a database. The DBMS manages user requests (and requests from other programs) so that users and other programs are free from having to understand where the data is physically located on storage media and, in a multi-user system, which else may also be accessing the data. A database is a collection of related information stored in a manner that it is available to many users for different purposes. The content of a database is obtained by combining data from all the different sources in an organization. So that data are available to all users and redundant data can be eliminated or at least minimized. The DBMS helps create an environment in which end user have better access to more and better managed data than they did before the DBMS become the data management standard. A database can handle business inventory, accounting information in its files to prepare summaries, estimates, and other reports. There can be a database, which stores new paper articles, magazines, books, and comics. There is already a welldefined market for specific information for highly selected group of users on almost all subjects. The database management system is the major software component of a database system. Some commercially available DBMS are INGRES, ORACLE, and Sybase. A database management system, therefore, is a combination of hardware and software that can be used to set up and monitor a database, and can manage the updating and retrieval of database that has been stored in it. Most database management systems have the following facilities/capabilities:  Creating of a file, addition to data, deletion of data, modification of data; creation, addition and deletion of entire files.  Retrieving data collectively or selectively.  The data stored can be sorted or indexed at the user's discretion and direction.

Queries DBMS COBOL / Fortran Operating System Database

The DBMS interprets and processes users' requests to retrieve information from a database. The following figure shows that a DBMS serves as an interface in several forms. They may be keyed directly from a terminal, or coded as high-level language programs to be submitted for interactive or batch processing. In most cases, a query request will have to penetrate several layers of software in the DBMS and operating system before the physical database can be accessed.

17

Components of Database Management System (DBMS)
There are five major components in Database Management System (DBMS) which are:1. Hardware
All computing system must have at least, one complete set of hardware to run. The DBMS and the applications also required hardware to run. Because of DBMS have integration of data in it processing, so the hardware needed can be range from a single PC, to a single mainframe or to a network of computers. The particular hardware required depends on the organization’s requirements and the DBMS used. Some DBMS requires a minimum amount of main memory and disk space to run like Microsoft Access, but minimum configuration may not necessarily give acceptable performance. Besides that some DBMS run only on particular hardware or Operating System (OS), such as Microsoft Access can be operate in Windows Operating System, while others run on a wide variety of hardware and OS.

2. Software
The next component needed in DBMS after the hardware is software. Software is a general term used to describe a collection of computer programs, procedures and documentation that perform some tasks on a computer system. Differ from hardware, software is an intangible objects inside the computer while hardware is a tangible part of objects inside the computer. The software component comprises the DBMS software itself and the application programs, together with the Operating System (OS), including network software if the DBMS is being used over a network. Technically, application programs are written in third-generation language (3GL) such as, C, C++, Java, Visual Basic (VB), COBOL, FORTRAN, ADA or PASCAL. Besides that, they are also written in fourth-generation language (4GL) such as Structured Query Language (SQL).

3. Data
Data is most important component of the DBMS environment. Data is a collection of numbers, characters, images or other outputs from devices to convert physical quantities into symbols, in a very broad sense. Such data is typically further processed by a human or input into a computer, stored and processed there, or transmitted (output) to another human or computer. Raw data is a relative term; data processing commonly occurs by stages, and the "processed data" from one stage may be considered the "raw data" of the next. The database contains the operational data and the metadata, the ‘data about data’. The data also incorporates the system catalogue. Besides that, data acts as a bridge between machine components and the human components.

18

4. Procedures
Procedures refer to the instructions and rules that govern the design and use of the database. The users of the system and the staff that manage the database require documented procedures on how to use or run the system. These may consist of instructions on how to log on the DBMS and use a particular DBMS facility or application program. It also relies on how to start and stop the DBMS and make backup copies of the database. In addition, it can handle hardware or software failures and change the structure of a table, reorganize the database across multiple disks, improve performance, or archive data to secondary storage.

5. People
For DBMS component, people are referring to the user who involved with this system. The people involved may the person who participate on the usage of DBMS such as Data Administrator, Database Administrator, Programmer or naïve user eventhough.

19

Facilities of Database Management System (DBMS)
There are three facilities of DBMS in commons:1. Data Definition Language (DDL)
Data Definition Language is a set of Structured Query Language (SQL) commands used to create, modify and delete database structures (not data). These commands wouldn't normally be used by a general user, who should be accessing the database via an application. They are normally used by the DBA (to a limited extent), a database designer or application developer. These statements are immediate; they are not susceptible to ROLLBACK commands. It allows user to define the database, specify the data types, structure and the constraint on the data to be stored in the database. DDL cannot be used to manipulate data.

2. Data Manipulation Language (DML)
Data manipulation language is the area of SQL that allows you to change data within the database. It provides set of operations to support the basic data manipulation operations on the data held in the database. It consists of only three command statement groups; they are INSERT, UPDATE and DELETE. DML having a central repository for all data and data descriptions allow the DML to provide a general inquiry facility to this data, called a query language. The provision of the query languages alleviates the problem with file-based systems where the user has to work with a fixed set of queries or there is a proliferation of programs, giving major software management problems. The common query language is the Structured Query Language (SQL). Besides that there are two types of DML:1. Procedural: User specifies how required data is retrieved. 2. Non-Procedural: User specifies what data is required without specifying how to get those data.

3. Provide Controlled Access to Database
1. Provide security system: Pevent database from being access by the unauthorized user. Database may provide user name and password that must be fill correctly in order to access the database 2. Provide integrity system: Data can be access by any user within same information and no data mistake between each data. 3. Provide concurrency control system: User can access to the database simultaneously without having problem. 4. Provide a recovery control system: Data can be recovering when there some file interrupted or lost by previous well-backup of data. 5. Provide a user accessible catalog: The information of data stored can be trace within data catalog or meta-data or even data-about-data.

20

Functions of Database Management System (DBMS)
1. Data Storage, Retrieval and Update
The function of data storage, retrieval and update help user to use database in DBMS. User can save the data in database. Besides that user can retrieve and update the data after the data saved. This functionality the DBMS should hide the internal physical implementation details from the user. For example, a manager of ITtoYou Sdn. Bhd. has save the data about his staff in Staff Information System. Later on, he/she or another manager want to update or change the data because of address mistake, therefore he/she just change the data needed without affecting the user view’s or application.

As example, we modify the word “Hamsah” to “Hamzah”

The data changed doesn’t affect other data and user view’s or application.

21

2. A User-Accessible Catalog
User accessible catalog means that user can now the preference of data stored in database. The data catalog as known as ‘meta-data’ or ‘data about data’ help user to known the amount of information of data that being stored. The catalog usually present in table. For example, a manager of Finance Department of ITtoYOU Sdn. Bhd wants to know the relations of data stored in Staff Information System, he/she can get the information from DBMS. RELATIONS Relation Name STAFF WORK WORK DEPARTMENT DEPARTMENT COLUMN Data Type Character (10) Character (30) Integer (15) Character (6) Character (12) Character (10) Character (20) ……… ……… ……… Character (10) No Of Column 5 3 3 2

Column Name Staff Id Name I/C Gender Qualification Ex ID Work ……. ……. ……. Title

Belongs To Relation STAFF STAFF STAFF STAFF STAFF WORK WORK ……… ……… ……… DEPARTMENT

3. Transaction Support
In DBMS, data can be transacted within user needed. Users just need to state the statement needed to the search engine, and the data need will appear. As example, if a department from ITtoYOU Sdn. Bhd want to know the information about staff work and qualification, they just need to key in the statement and the data needed will transact.

4. Concurrency Control Services
Totally in database, users can use the database simultaneously. It also same in DBMS whereby user have the right to access the data simultaneously but the concurrency usage must be control to prevent the data clash at the same time. For example, concurrency control services prevent two departments in ITtoYou Sdn. Bhd from change the data about same staff simultaneously. Another department must wait until other department have changed the

22

data. They just have the right to access the data but not to retrieve or update the data.

5. Recovery Services
Other function of DBMS is recovery services whereby DBMS will restore the loss or damage data with previous well data. The data can be back up automatically or manually at the time where the data in good condition. As example, if Staff Information System in ITtoYOU Sdn. Bhd had damaged because being attacked by a virus, DBMS will restore previous well condition data to re-operate the system back.

6. Authorization Services
DBMS can prevent the data lost and damage from unauthorized user. By using authorization services, users need to key in the username and password correctly to have the access to the database. It is because the data must be keeping from unauthorized user to prevent from user source and information interrupted or corrupted. One example based on scenario given, other department in ITtoYOU Sdn. Bhd. do not have the right to access Production Department without the authorization. They must get the correct username and correct password to access the data in Production Department.

7. Support of Data Communication
Data communication support is another function of DBMS which help user to find an identify data related to the data need. The relations between data make the user to know the other related information of the data. Data integration helps the data communication. If the Accounting Department in ITtoYOU Sdn. Bhd have a right to access certain data, they still can know other information of the data because of the data redundancy and data communication.

23

8. Integrity Services
An integrity service is mean by data storage and modified have the thrust to the certain rules provide by DBMS. For example, when users want to change or enter another data in Staff Information System of ITtoYOU Sdn. Bhd. they must follow the limit stated by DBMS. If the limit of the data is 20 characters only, so the users just only have the right to enter 20 characters only.

9. Services to Promote Data Independence
Data independence is a concept of data and applications determines as two separate entities which each entity do not affect each other. Therefore services to promote data independence Is another function to the DBMS. These services are needed to make the changing of data easier. As example, if the unit of ITtoYOU Sdn. Bhd want to update the data in Staff Information System, they just need to change or retrieve it without changing the application and user view’s.

10.Utility Services
These services are services of DBMS utilise to user needed, such as data back up or data recovery. The utility of data back up for example may help user to recover data when needed either manually or automatically. For example, when ITtoYOU Sdn. Bhd need a file recovery for Staff Information System, they can get it from previous back up data either the data have been back up manually or automatically like nightly backup.

24

Roles in Database Environment
1. Data Administrator (DA)
Responsible for the management of the data resource including database planning, development and maintenance of standards, policies and procedures, and conceptual/logical database design. DA consults with advices senior manager ensuring that the direction of database and cooperate with the Database Administrator (DBA) and database development so that it fulfil the user’s need.

2. Database Administrator (DBA)
DBA responsible for the physical realization of the database, including physical database design and implementation, security and integrity control, maintenance of the operational system, and ensuring satisfactory performance of the application for users. DBA also choose the DBMS product and train users.

3. Database Designer
In the large database design projects, we can distinguish between two types of designer which is:-

 Logical Database Designer
This designer concerned with identifying the data (which is the entitles and attributes), the relationships between data and the constraints on the data stored in database. This designer just predicts the abstract design of the database but this designer must have the through and understanding of data and any constraints.

 Physical Database Designer
This designer design new and logical database design to be physical realized. Rather than Logical Database Designer that predicts an abstract design outcome, this designer transfer the abstract view of design to the physical design. Besides that, this designer design security measured required on the data and selecting specific storage structures and access methods for the data to achieve good performance.

4. Application Developer
Application developer implemented the application programs that provide functionally for the end users. Usually, the application developers work from a specification produced by system analysis

5. End-Users
The end-users area the clients for the database, which has been designed and implemented, and is being maintained to serve their information needs. Endusers can be classified according to the way use the system:-

 Naive Users
These users are definite as a person that unaware of the usage the DBMS, Invoke database operations by entering simple commands or choosing options from a menu. These are means that they do not compulsory need to know anything about the database or the DBMS.

25

 Sophisticated Users
These users are familiar with the structure of the database and facilities offered by the DBMS. They may use high level query language such as Structured Query Language (SQL) to perform required operation and some sophisticated end-users may even write applications programs for their own use.

26

Advantages of Database Management System (DBMS)
1. Control of Data Redundancy
The usage of Database Management System (DBMS) prevents data from being redundant or duplicate by the control of primary key. By using the DBMS, when a primary key have been set up, similar data within similar information and similar key will be prevent with this message.

If this duplication of data was occurred, this message box will appeared to inform the user that the data have been redundant.

Therefore, from both diagram above, its showed that DBMS have the advantage of controlling the data from being redundant. The database approach attempts to eliminate the redundancy by integrating the files so that multiple copies of the same data are not stored. However, the database approach does not eliminate redundancy entirely, but controls the amount of redundancy inherent in the database. For example, foreign key still one of redundant data but it is less than redundancy of whole data like in file base.

27

2. Data Consistency
By eliminating or controlling data redundancy, we reduce the risk of inconsistencies occurring. If a data item is stored only once in the database, any update to its value has to be performed only once and the new value is available immediately for all users. For example if a data about staff is stored more than once and the system aware of this, the system can ensure that all copies of staff information are kept consistent. Example use is similar to the database advantages of less duplication of data but the main point refers is about data consistency

As example, we modify the word “Hamsah” to “Hamzah”

Automatically the data in other file will change. This shows that less duplication of data in database.

28

3. More Information from The Same Amount of Data
Each advantages are connected each other, so within the integrated of operational data, it may possible for the organization to derive additional information from the same data. As example, the Accounting Department does not know who the staff of Human Resource Department. Similarly, the Human Resource Department has no knowledge of who is in-charged in accounting. When we integrated these files, users consist of managers in these two departments can access all the details. We now are able to derive more information from the same amount of data.

Human Resource Department may want to know the information about the staff who work on Accounting Department just by searching on department code and the staff ID will be shown. While, if Accounting Department want to know about the staff information, user just state the statement needed and the information about the staff will appeared.

From these example that have be shown above, we can considered that more information from the same amount of data can be approve within the integrated of relational data.

29

4. Sharing of Data
By using Database Management System, data can be shared by any users. The information stored will be shared by the user need. But typically, files are owned by the people or an organization that use them. The database belongs to the entire organization and can be shared by all authorized users. For approving this advantage, one example of data sharing is shown below.

This is the complete data of all staff information file. From database, we can grab and shared the data needed by just key in the statement needed.

30

5. Improves Security
One of the Database Management System advantages are improves security. How the usage of DBMS can improves security? It is meant by database is secured from unauthorized users. Without suitable security measures, integration makes the data more vulnerable than file-based system. However, there is another way to get the data from DBMS. The advantage of DBMS of improves data integrity allows the Database Administrator to define, and the DBMS to enforce database security. This may take the form of user names and passwords to identify people authorized to use the database. For example, the Database Administrator may have the right to access all data in database but for the Human Resource Department may need to enter the username and password to have the right of access. So the data interruption or data loss can be prevent by this security to the authorized user only

6. Economy of Scales
Combining all the organization’s operational data into one database, and creating a set of applications that work on this one source of data, can result in cost savings. In this case, the budget that would normally be allocated to each department for the development and the maintenance of its file-based system can be combined, possibly resulting in a lower total cost, leading to an economy scale. The combined budget can be used to buy a system configuration that is more suited to the organization’s needs. This may consist of one large, powerful computer or a network of smaller computer. For example, if a company need to establish their own Database Management System, data integrity may reduce the cost of maintenances of the database. Besides that, less time and money needed because the data can be search by the end of fingertip. The user may no need to go for each department to search the data and information needed.

31

7. Enforcement of Standards
Enforcement of standards within the data integrity may make Database Administrator easier to define and enforce the necessary standards. These may include departmental, organizational, national or international standards for such things as data formats to facilitate exchange of data between system, naming conventions, documentation standard, update procedures, and access rules. The data also can be secured with enforcement of standards. As example, if the user has to make a change to the staff information data like address or state, he/she just search or find the information needed and the data will appear.

Example above approve that the enforcement of standard will limit the data access. If the data is standardize only for Bahagian Teknologi Maklumat so the result is just beyond the Bahagian Teknologi Maklumat data.

32

8. Improved Backup and Recovery Services
Many file-based systems place the responsibility on the user to provide measure to protect the data from failures to the computers system or application program. This may involve taking automatically backup such as nightly backup of the data. In the event of failure during the next day, the backup is restored and the work that has taken place since this backup is lost and to be re-entered. In contrast, modern Database Management System provides facilities to minimize the amount of processing that is lost following a failure.

33

Examples of Database Management System (DBMS)
CODASYL DBMS
CODASYL (often spelt Codasyl) is an acronym for "Conference on Data Systems Languages". This was an Information technology industry consortium formed in 1959 to guide the development of a standard programming language that could be used on many computers. This effort led to the development of COBOL. CODASYL's members were individuals from industry and government involved in data processing activity. Its larger goal was to promote more effective data systems analysis, design, and implementation. The organization worked on various languages over the years but never actually standardized one. The standardization process was left to ANSI. CODASYL DBMS is a multi-user, CODASYL-compliant database management system for OpenVMS operating systems. CODASYL DBMS is designed for databases of all levels of complexity, ranging from simple hierarchies to sophisticated networks with multilevel relationships. CODASYL DBMS provides a reliable operating platform for application environments where stability, high availability, and throughput are essential. CODASYL DBMS provides options supporting very large memory addressing and hot standby for performance and availability. Release 7 also offers added improvements for reliability to manufacturing and shop floor control environments using this database. Very Large Memory Addressing Support: A shared record cache allows the DBMS to use as much physical memory as a computer system can support, so that frequently accessed records can be stored in memory and reduce disk I/O. The advantages include reduced overhead and improved response time.

Hot Standby: The Hot Standby prevents the DBMS database from becoming a
single point of failure by physically duplicating the database at a geographically remote site. In the event of failure, the "hot standby" database becomes the master database and takes over application processing. This does not require specific hardware to operate, and no changes to the application code are needed.

Hardware and Software Requirements: Oracle CODASYL DBMS runs on
any valid Digital Alpha or VAX configuration running the Open VMS operating system

34

Database Management
     Easy-to-use utility command language (DBO) Database Restructuring Utility (DRU) provides the ability to change many database characteristics without unloading and reloading the database Initial Load utility; Unload utility for data extraction; functionality for database restructuring with Unload/Load Simple restructuring, including adding AREAS and initializing AREAS, without unloading and reloading a database Interactive Database Query utility (DBQ) with video display of subschema structure diagrams on VT100, VT200, or VT300 compatible terminals

35

Roles of Database Administrator in Developing Staff Information System
As a Database Administrator of Staff Information System, I think there have much responsibility to develop a database system for ITtoYOU Sdn. Bhd. This is because without Database Administrator, the database system cannot be constructed very well. It may bring a lot of problem to organize the large number of information about staff details without Database Administrator. As Database Administrator, I must find out the best and suitable kind of data for the Staff Information System. Also, Database Administrator is responsible for the management of the data resource including database planning, development and maintenance of standards, policies and procedures, and conceptual or logical database design. For example, like the Staff Information System for ITtoYOU Sdn. Bhd. I have determined the best way to make this system can be used by all users. Moreover, it can improve the system for ITtoYOU Sdn. Bhd. Database administrator also improves security by defining or implementation access control of the data. In fact, it can avoid the unauthorized users by using the system. Furthermore, as a database administrator who develops the system is quiet importance to know and understand the system so that all information can be stored, update and retrieve easily without having any problem in the future. Besides that, the Data Administrator has the primary responsibility of consulting with and advising the company administrator and ensuring that the application and direction of the database development system continues to ultimately support the corporate objectives. Also, Database Administrator can co-operate with Data Administrator and Database Development so that it fulfils the ITtoYOU Sdn. Bhd’s need. This is why database administrator is the important roles in developing the Staff Information System for ITtoYOU Sdn. Bhd.

36

Problems of File-Based on Developing Staff Information System
By using file-based on developing Staff Information System, data will have a certain limitations which become a major problem to the whole system. The disadvantages of these limitations are:-

1. Separation and Isolation of Data
The data cannot be integrated with other file and temporary data may need to create as a reference. It will make the system become worse because the data needed in Staff Information System maybe a hundred or thousand which difficult the data references. ITtoYou Sdn. Bhd. May have lack of productivity because the data is separate and isolate to each data.

2. Duplication of Data
Other problems that will occurred on Staff Information System development if used file-based is duplication of data. Too much data will be redundant and it is wasteful of productivity and maintenance. Duplication is wasteful from it costs of time and money. Moreover it takes up additional storage spaces which lead to lackness of space beyond. Although it can lead to loss of data integrity and inconsistent when they need to update or retrieve. A lot of changing is needed to each file to make sure the data integrity.

3. Data Dependence
The physical structure and storage of the data files and records are defined in the application code. Staff Information System in ITtoYOU may require the creation of one-off program that converts the particular file to the new format.

4. Incompatible File Formats
The structure of files is embedded in the application programs, and the structures are dependent on the application programming language. The direct incompatibility of such files makes them difficult to process jointly. The applications programs (files) may be generated by different programs like COBOL and C++. Although, incompatible file formats make the structure of file is dependant on the programming language for Staff Information System for the ITtoYOU Sdn. Bhd. Moreover, the direct incompatibility of such files makes them difficult to process jointly.

5. Fixed Queries
Fixed queries or proliferation of application programs, it proved to be a great improvement over manual systems. The requirement for new or modified queries grew. For Staff Information System in ITtoYOU Sdn. Bhd there is no provision for security or integrity and in the event of a hardware or software failure was limited or non-existent when the development is using file-based. No facilities for asking unplanned queries and the right of access to the files war restricted

37


				
DOCUMENT INFO
Description: Pelajar-pelajar universiti pasti mahukan contoh assignment database. So, inilah dia contoh lengkap assignment database