Traditional File Systems Essay

Traditional File Systems Essay The traditional filing system (TFS) is a method of storing and arranging computer files and the information in the file (data). Basically it organizes these files into a database for the storage, organization, manipulation, and retrieval by the computers operating system. (DBMS) consists of software that operates databases, providing storage, access, security, backup and other facilities. This system can be categorized according to the database model and the type of computer that they support such as a server cluster or a mobile phone, the query language(s) that access the database, such as SQL or XQuery, performance trade-offs, such as maximum scale or maximum speed or others. Some DBMS cover more than one entry in these categories, e.g., supporting multiple query languages. Meanwhile database management systems are usually accessed in a client-server manner, where the database client and the server are located on different machines (in a local area network). Both systems deal with information management. File-based System File-based systems were an early attempt to computerize the manual filing system. File-based system is a collection of application programs that perform services for the end-users, such as updating, insertion, deletion adding new files to database etc. Each program defines and manages its data. When a computer user wants to store data electronically they must do so by placing data in files. Files are stored in specific locations on the hard disk (directories). The user can create new files to place data in, delete a file that contains data, rename the file, etc which is known as file management; a function provided by the Operating System (OS). Disadvantages of traditional file based system No need of external storage Provides less security. No need of a highly technical person to handle the database. Redundancy is more. Processing speed is high as compared to DBMS Less integrity. High complexity in updating of database. Table 1.1.1 Database Management System The improvement of the File-Based System (FBS) was the Database Management System (DBMS) which came up in the 60s. The Database Management System removed the trouble of manually locating data, and having to go through it. The user could create a suitable structure for the data beforehand, to place the information in the database that the DBMS is managing. Hence, the physical organizing of files is done away with and provides the user with a logical view of the data input. A database is a collection of interrelated information stored in a database server; these data will be stored in the form of tables. The primary aim of database is to provide a way to store and retrieve database information fast and in an efficient manner. Advantages Control of data redundancy Although the database approach does not remove redundancy completely, it controls the amount of redundancy in the database. Data consistency By removing or controlling redundancy, the database approach reduces the risk of inconsistencies occurring. It ensures all copies of the idea are kept consistent. More information from the same amount of data With the amalgamation of the operated data, it is possible to derive additional information for the same data. Sharing of data Database belongs to the entire organization and can be shared by all authorized users. Improved data integrity Database integrity provides the validity and consistency of stored data. Integrity is usually expressed in terms of constraints, which are consistency rules that the database is not permitted to violate. Improved security Provides protection of data from unauthorized users. It will require user names and passwords to identify user type and their access right in the operation including retrieval, insertion, updating and deletion. Enforcement of standards The integration of the database enforces the necessary standards including data formats, naming conventions, documentation standards, update procedures and access rules. Economy of scale Cost savings can be obtained by combining all organizations operational data into one database with applications to work on one source of data. Balance of conflicting requirements By having a structural design in the database, the conflicts between users or departments can be resolved. Decisions will be based on the base use of resources for the organization as a whole rather than for an individual person. Improved data accessibility and responsiveness By having integration in the database approach, data accessing can cross departmental boundaries. This feature provides more functionality and better services to the users. Increased productivity The database approach provides all the low-level file-handling routines. The provision of these functions allow the programmer to concentrate more on the specific functionality required by the users. The fourth-generation environment provided by the database can simplify the database application development. Improved maintenance Provides data independence. As a change of data structure in the database will affect the application program, it simplifies database application maintenance. Increased concurrency Database can manage concurrent data access effectively. It ensures no interference between users that would not result any loss of information or loss of integrity. Improved backing and recovery services Modern database management system provides facilities to minimize the amount of processing that can be lost following a failure by using the transaction approach. Disadvantages Complexity A difficult software. All users must be familiar with its functionality and take full advantage of it. Therefore, training for the administrators, designers and users is required. Size Uses a substantial amount of main memory as well as large amount of disk space in order to make it run efficiently. Cost of DBMS A multi-user database management system may be very expensive. Even after the installation, there is a high regular annual maintenance cost on the software. Cost of conversion When moving from a file-base system to a database system, the company is required to have additional expenses on hardware acquisition and training cost. Performance As the database approach is to cater for many applications rather than exclusively for a particular one, some applications may not run as fast as before. Higher impact of a failure Increases the vulnerability of the system due to the centralization. As all users and applications reply on the database availability, the failure of any component can bring operations to a halt and affect the services to the customer seriously. The difference between TFS and DBMS Balajee B. (2005), There are number of characteristics that differ from traditional file management system to database management system. In file system approach, each user implements the required files for a specific application to run. (Example: in a sales department of an enterprise, one user will be maintaining the details of the number of sales personnel in that department and their grades. These details will be stored and maintained in a separate file. Another user will maintain the salary details of these sales personnel and the detailed salary report will be stored and maintained in a separate file. Although both of the users need the data of the salespersons, they will be having their details in separate files and they need different programs to operate their files.) When such data is isolated in separate files, it is difficult to access data that should be available for both users. This will lead to wastage of space and redundancy or replication of data, which may lead to c onfusion, as sharing of data among various users is not possible and data inconsistency may occur. These files will not be having any inter-relationship among the data stored in these files. Therefore in traditional file processing every user will be defining their own constraints and implement the files according to their needs. In database approach, a single store of data is maintained that is defined once and then accessed by many users, as database belongs to the entire organization and can be shared by all authorized users. The essential characteristic of database approach is that the database system not only contains data but it contains complete definition or description of the database structure and control. These definitions are stored in a system catalog, which contains the information about the structure and definitions of the database. The information stored in the catalog is called the metadata, it describes the primary database. Hence this approach will work on any type of database for example, insurance database, Airlines, banking database, Finance details, and Enterprise information database. But in traditional file processing system the application is developed for a specific purpose and they will access specific database only. But the processing speed in TFS is high compared to DBMS. The other main characteristic of the database is that it will allow multiple users to access the database at the same time and sharing of data is possible. The database must include concurrency control software to ensure that several users trying to update the same data at the same time, it should maintain in a controlled manner. In file system approach many programmers will be creating files over a long period and various files have different format, in various application languages, where duplication of data can occur. This redundancy in storing same data multiple times leads to higher costs and wastage of space. This may result in data inconsistency in the application; this is because update is done to some of the files only and not all of the files. Moreover in database approach multiple views can be created; External view User/Application view, Conceptual view Logical view, Internal view Details about the structure of data and physical storage of information. View is a tailored representation of information contained in one or more tables. View is also called as Virtual table because view does not contain physically stored records and will not occupy any space. A multi-user database whose users have variety of applications must provide facilities for defining multiple views. In traditional file system, if any changes are made to the structure of the files it will affect all the programs. Therefore, changes to the structure of a file will require to change all programs that access the file and whereby data dependence will be lost. But in the case of database approach the structure of the database is stored separately in the system catalog from the access of the application programs. This property is known as program-data independence. Database can also be used for continuous storage for program objects and data structures that resulted in object oriented database approach. Traditional systems suffered from impedance mismatch problem and difficulty in accessing the data, which is avoided in object oriented database system. Database can be used to represent complex relationships among data as well as to retrieve and update related data easily and efficiently. Hence DBMS does not automatically remove redundancies, but help to control redundancy. It is possible to define and enforce integrity constraints for the data stored in the database. The database also provides facilities for recovering hardware and software failures, as it has automatic and intelligent backup and recovery procedures. It reduces the application development time considerably when compared to the file system approach and availability of up-to-date information of all the users. It also provides security to the data stored in the database system and maintains integrity. A highly technical person will be required to handle the database, while for TFS, it is not so. File-based systems are very dependent upon the application programmer. Any required queries or reports have to be written by the application programmer. Normally, a fixed format query or report can only be entertained and no facility for ad-hoc queries if offered. DBMS has data independence. The way information is stored and the way information issued is independent of each other. File-based systems also give tremendous pressure on data processing staff, with users complaints on programs that are inadequate or inefficient in meeting their demands. Documentation may be limited and maintenance of the system is difficult. Provision for security, integrity and recovery capability is very limited. Whereas, DBMS has control over security as it provides tools such as use of User Code, Password / Privileges and Roles to ensure security of data. Data, Field, Record, and File are the main components of Database environment. Briefly explain those. Data Webopedia (Anon., n.d.), Distinct pieces of information usually formatted in a special way. All software is divided into two general categories: data and programs. Programs are collections of instructions for manipulating data. Data can exist in a variety of forms as numbers or text on pieces of paper, as bits and bytes stored in electronic memory, or as facts stored in a persons mind. Strictly speaking, data is the plural of datum, a single piece of information. In practice, however, people use data as both the singular and plural form of the word. The term data is often used to distinguish binary machine-readable information from textual human-readable information. For example, some applications make a distinction between data files (files that contain binary data) and text files (files that contain ASCII data). In database management systems, data files are the files that store the database information, whereas other files, such as index files and data dictionaries, store adminis trative information, known as metadata. Field Webopedia (Anon., n.d.), A space allocated for a particular item of information. A tax form, for example, contains a number of fields: one for your name, one for your Social Security number, one for your income, and so on. In database systems, fields are the smallest units of information you can access. In spreadsheets, fields are called cells. Most fields have certain attributes associated with them. For example, some fields are numeric whereas others are textual; some are long, while others are short. In addition, every field has a name, called the field name. In database management systems, a field can be required, optional, or calculated. A required field is one in which you must enter data, while an optional field is one you may leave blank. A calculated field is one whose value is derived from some formula involving other fields. You do not enter data into a calculated field; the system automatically determines the correct value. A collection of fields is called a record. Record Webopedia (Anon., n.d.), In database management systems, a complete set of information. Records are composed of fields, each of which contains one item of information. A set of records constitutes a file. For example, a personnel file might contain records that have three fields: a name field, an address field, and a phone number field. In relational database management systems, records are called tuples. Some programming languages allow you to define a special data structure called a record. Generally, a record is a combination of other data objects. For example, a record might contain three integers, a floating-point number, and a character string. In database management systems, a complete set of information. Records are composed of fields, each of which contains one item of information. A set of records constitutes a file. For example, a personnel file might contain records that have three fields: a name field, an address field, and a phone number field. Figure 1.2.1 Source Author Anon., File Webopedia (Anon., n.d.), A collection of data or information that has a name, called the filename. Almost all information stored in a computer must be in a file. There are many different types of files: data files, text files, program files, directory files, and so on. Different types of files store different types of information. For example, program files store programs, whereas text files store text. What is the Importance of DBMS in a Defense Organization and in an Education Department? Defence Organization Benjamin (n.d.), A Database Management System (DBMS) is a set of computer programs that controls the creation, maintenance, and the use of the database with computers of an organization and its end users. It allows organizations to place control of organization-wide database development in the hands of database administrators (DBAs) and other specialists. As organizations develop with time, their adoption to the latest technologies in the computer field becomes a necessity. A Defence organization is no different. In these turbulent times, when national security is more important, providing all Defence personnel with access to the latest technology and education opportunities not only directly contributes to Defence capability but also improve the defence personnels career development. Hence the importance of a DBMS in such an organization like Defence is vital. Because Database administrators could use this system to configure and operate databases as the software provides high level, privileged database access. But the management should restrict use of this software to authorized personnel. One function of the database administrator is to create particular views of information stored in the database that are unique for each type of user. For example, one officer will have a different view of information in the database than another, say Senior officer. The different user groups will also have different abilities to add, modify, or delete information. The database administrator is responsible for providing users with access to the appropriate level of information. The primary risk associated with database administration is that an administrator can alter sensitive data without those modifications being detected. A secondary risk is that an administrator can change access rights to information stored within the database as well as their own access rights. Database security is the last line of defence. So it deserves greater focus on the protection of private data from both internal and external. The sensitivity and classification of the information stored in the database form the basis for establishing controls. A database that stores confidential information may require a more significant control environment than a database that stores non-sensitive information. Management should consider the security and performance implications of the security options available with modern database management systems. Database security professionals and information security and risk management professionals could adopt a security strategy in DBMS to: 1) Align database security policies with information security policies; 2) Ensure well-defined and formalized database security procedures; 3) Enforce role separation; and 4) Apply advanced security measures such as database auditing, monitoring, database encryption, data masking, and vulnerability assessment to all critical databases that store private data. The DBMS can provide long-term benefits for the Defence organization reducing duplication of data and making it easier for HR to update personnel records. If not for DBMS, each time there was a personnel change, trainers would have to go through their entire content to make the necessary changes. Now, replacing Brigadier Xs picture in the content library with Commodore Ys picture can be automatically replicated through all relevant programs. Thereby reduce its expenditure on storage. But, initial training will be required for all programmers and users. Even though database systems are complex, difficult, and time-consuming to design, there is greater data integrity and independence from applications programs and Education Department Sue Bushell (2004), To improve teaching and learning with the help of modern information and communication technology eLearning is beneficial to education, corporations and to all types of learners. It is affordable, saves time, and produces measurable results. E-learning comprises all forms of electronically supported learning and teaching. The Information and communication systems, whether networked or not, serve as specific media to implement the learning process. E-learning services have evolved since computers were first used in education. There is a trend to move towards blended learning services, where computer-based activities are integrated with practical or classroom-based situations. E-learning is essentially the computer and network-enabled transfer of skills and knowledge. E-learning applications and processes include Web-based learning, computer-based learning, virtual classroom opportunities and digital collaboration. Content is delivered via the Internet, intranet/extranet, audio or video tape, satellite TV, and CD-ROM. It can be self-paced or instructor-led and includes media in the form of text, image, animation, streaming video and audio The definition of e-learning varies depending on the organization and how it is used but basically it involves electronic means of communication, education, and training. Regardless of the definition you chose to use, designers, developers, and implementers make or break the instructional courses and tools. E-learning is simply a medium for delivering learning and like any other medium, it has its advantages and disadvantages. E-learning covers a wide array of activities from supported learning, to blended or hybrid learning (the combination of traditional and e-learning practices), to learning that occurs 100% online. As per wikipedia.org, the worldwide e-learning industry is estimated to be worth over $48 billion US according to conservative estimates. Developments in internet and multimedia technologies are the basic enabler of e-learning, with consulting, content, technologies, services and support being identified as the five key sectors of the e-learning industry. E-learning is naturally suited to distance learning and flexible learning, but can also be used in conjunction with face-to-face teaching, in which case the term Blended learning is commonly used. E-Learning pioneer Bernard Luskin argues that the E must be understood to have broad meaning if e-learning is to be effective. Luskin says that the e should be interpreted to mean exciting, energetic, enthusiastic, emotional, extended, excellent, and educational in addition to electronic that is a traditional national interpretation. This broader interpretation allows for 21st century applications and brings learning and media psychology into the equation. E-Learning can also refer to educational web sites such as those offering learning scenarios, worksheets and interactive exercises for children. The term is also used extensively in the business sector where it generally refers to cost-effective online training There are many advantages to online and computer-based learning when compared to traditional face-to-face courses and lectures. There are a few disadvantages as well. Advantages of eLearning (Anon., n.d) E-learning is beneficial to education, corporations and to all types of learners. It is affordable, saves time, and produces measurable results. Cost effective E-learning is more cost effective than traditional learning because less time and money is spent traveling. Since e-learning can be done in any geographic location and there are no travel expenses, this type of learning is much less costly than doing learning at a traditional institute. Flexibility Flexibility is a major benefit of e-learning. E-learning has the advantage of taking class anytime anywhere. Education is available when and where it is needed. E-learning can be done at the office, at home, on the road, 24 hours a day, and seven days a week. Learners like e-learning because it accommodates different types of learning styles. They have the advantage of learning at their own pace. Students can also learn through a variety of activities that apply to many different learning styles. Learners can fit e-learning into their busy schedule. If they hold a job, they can participate in eLearning right at their desk. If the learner needs to do the learning at night, then this option is available while in their pyjamas and do the learning if they desire. Personalized learning E-learning encourages students to peruse through information by using hyperlinks and sites on the worldwide Web. Learners are able to find information relevant to their personal situations and interest. E-learning allows selection of learning materials that meet their level of knowledge, interest and what they need to know to perform more effectively in an activity. E-learning is more focused on the learner and it is more interesting for the learner because it is information that they want to learn. E-learning is flexible and can be customized to meet the individual needs of the learners. Develops knowledge E-learning helps develop knowledge of the Internet. This knowledge will help learners throughout their careers. E-learning encourages students to take personal responsibility for their own learning. When learners succeed, it builds self-knowledge and self-confidence Disadvantages of eLearning Access One disadvantage of eLearning is that learners need to have access to a computer as well as the Internet. They also need to have computer skills with programs such as word processing, Internet browsers, and e-mail. Without these skills and software it is not possible for the learner to succeed in eLearning. E-learners need to be very comfortable using a computer. Slow Internet connections or older computers may make accessing course materials difficult. This may cause the learners to get frustrated and give up.   Software and files Another disadvantage of e-learning is managing computer files, software comfortability and learning new software, including e-learning. For learners with beginner-level computer skills it can sometimes seem complex to keep their computer files organized. The lesson points you to download a file which the learner does and later cannot find the file. The file is downloaded to the folder the computer automatically opens to rather than a folder chosen by the learner. This file may be lost or misplaced to the learner without good computer organizational skills. High motivation E-learning also requires time to complete especially those with assignments and interactive collaborations. This means that students have to be highly motivated and responsible because all the work they do is on their own. Learners with low motivation or bad study habits may not complete modules and may fall behind Isolation Another disadvantage of e-learning is that students may feel isolated and unsupported while learning. Instructions are not always available to help the learner so learners need to have discipline to work independently without assistance. E-learners may also become bored with no interaction with instructors or classmates.   Without the routine structures of a traditional class, students may get lost or confused about course activities and deadlines. Instructor may not always be available when students are studying or need help Conclusion Today many technologies can be, and are, used in e-learning, from blogs to collaborative software, E-Portfolios, and virtual classrooms. Most e-learning situations use combinations of these techniques. Even though the hardware and software start-up are costly, the advantages are; reduced data redundancy, reducing updating errors and increased consistency, greater data integrity and independence from applications programs, improved data access to users through use of host and query languages, improved data security and availability of facilitated development of new application programs and ability for intensive research are the benefits of DBMS. Task 2 Draw an Entity Relationship Data Model which describes the content and structure of the data held by the Medi Check Hospital. Produce the resulting tables of above Medi Check Hospital and clearly indicating the primary and foreign keys. Data Tables Doctor DoctorID (primary) Lname Fname Address Phone Pager Specialty Location Availability Patient PatientNo (primary) PatientFirstName PatientLastName PatientAddress PatientTelNo PatientDob PatientMaritalStatus PatientDateRegistered Appointment AppointmentNo (primary) PatientName Date/Time PatientTelNo Symptom SymptomCode (primary), SymptomName Description Treatment TreatmentTitle (primary) TreatmentType Duration Status TreatmentCost Medication MedicationNo (primary) MedicationType SideEffect Dosage Frequency Severity MedicationBrandName MedicationManufactureName MedicationManufactureAddress MedicationManufactureTel Normalize these tables to ensure that are all in BCNF. Show the steps you have taken in normalizing the tables. UNF Medication (DoctorID, Lname, Fname, Address, Phone, Pager, Specialty, Location, Availability, PatientNo, PatientFirstName, PatientLastName, PatientAddress, PatientTelNo, PatientDob, PatientMaritalStatus, PatientDateRegistered, AppoinmentNo, PatientName, Date/Time, PatientTelNo, SymptomCode, SymptomName, Description, TreatmentTitle, TreatmentType, Duration, Status, TreatmentCost, MedicationNo, MedicationType, SideEffect, Dosage, Frequency, Severity, MedicationBrandName, MedicationManufactureName, MedicationManufactureAddress, MedicationManufactureTel) 1NF Doctor Details (DoctorID, Lname, Fname, Address, Phone, Pager, Specialty, Location, Availability) Patient Details (PatientNo, PatientFirstName, PatientLastName, PatientAddress, PatientTelNo, PatientDob, PatientMaritalStatus, PatientDateRegistered, AppoinmentNo, PatientN

Greek and Roman Architecture

Running Head: Greek and Roman Architecture Greek and Roman Architecture By: Michelle Garrotters Art 101 November 2nd, 2008 Head: Greek and Roman Architecture Compare the characteristics and innovation of each Greek and Roman Architecture. The Greek and Roman architecture is very impressive for not only their time but also in our time today. The Greek architecture uses the columns in almost all of their temples. The shapes of the columns were extremely important to the Greeks. They used three different types of columns. The â€Å"Doric†, â€Å"Ionic†, and the â€Å"Corinthian†.All of these columns have a center piece that would be for displaying their Greek God(s) with what ever decorations. The Temple of Olympian Zeus is an example of â€Å"Corinthian† columns. The Temple of Poseidon is an example of â€Å"Doric† columns, and Athens is an example of â€Å"Ionic† columns. The Greeks usually built with either mud, wood, plaster, and/or stone. M ost of their buildings have not stood the test of time. Only temples made with marble or limestone these were built as objects of art honoring their different gods. These have been able to withstand the damage that time brings.The Roman architecture used mostly arches in their works. Which held more weight than the columns. Yes they used columns but only as decoration because of the weight. The Pantheon in Rome is a great example of this architecture. This building housed two kings and is one of the biggest surviving building in Rome. Romans used the same materials as the Greeks especially the Marble and Limestone. But they perfected the use of concrete, which is what most of their structures are made with. Most of the Romans buildings that are still preserved today are amphitheaters, bathhouses, aqueducts, and public housing. Unlike the Greeks theRomans did their buildings with lots of ornate on both inside and outside reflecting the â€Å"Pursuit of Pleasure† which is an es sential part of the Roman culture. In summary, Greek architecture is more rectilinear and of â€Å"post and lintel† construction. Greek buildings usually rectilinear, consisted off pediment supported by columns on a plinth for a base. Romans mastered the arch and the dome. Concrete made it possible to have more complex forms. Columns were used in both with the Greek favoring the Doric and Ionic for the cleaner lines. While the Romans preferred to use the more ornate Corinthian style columns.

Essay on Technology - Database Design Concepts

Essay Sample on Technology A Database Management System (DBMS) is required to store, retrieve and manipulate data from a database. according to Healey, the term DBMS will be used to refer to a software package for a storage, manipulation and retrieval of data from a database. a database is a collection of one or more data files or tables stored in a structured manner, such that interrelationships which exist between different items or sets of data can be utilized by the DBMS software for manipulation and retrieval purposes. The basic infrastructure to build other organizational information systems is a DBMS. Key Issues and applications of the DBMS There are several different issues related to data management in an organization environment. Filing system was adequate only for data storage, although not very efficient but it fulfilled the requirements of long-term data storage. Data retrieval was one of the major issues in file-based systems but with the advent of Database Management Systems and its quick and speedy retrieval methodology this issue was resolved. In the context of Dublin City Council Housing Project, some basic forms connected to a well-designed database will do the trick for data storage making it as effective and efficient as possible. Data retrieval can be performed more quickly compared to file based system. String based search and a few clicks is all that is required to get the required data from system. Updating of data is also a problematic area when database management system is not used. For Dublin City Housing, some part of data is ever changing like the apartment in which a particular household is residing. People move to different places and this information will be modified more frequently than other data. With a database system, it will take a few clicks to get this updated across the whole system. another key issue is analytical reporting. Imaging how hard it will be to figure out from a filing system that how many 2-bedroom apartments are vacant in the whole housing complex. With the native query language (SQL) of database, it is now a matter of seconds and you get your desired results. These are the basic issues that database management systems cater to however the benefits and applications are innumerable. Features and advantages of MS-access Compatibility It is compatible with all Microsoft products since it is a product of Microsoft, as well. User friendly Since it is a Microsoft Product, users are highly familiar with the interface as it has similar look and feel, which makes it user friendly. It is also very easy to use compared to other database systems. Scalable It is possible that the housing development and apartments might grow with time. MS access has upgrade capabilities so in case Dublin City Council Housing need to grow they can upgrade to SQL Server. Backup Dublins housing data can be easily backed up, frequently. So it is available in case of need. Cost effective Dublin Housing will not have to spend heavily on its DBMS if MS access is being used. Setup and Maintenance cost is also less, as compared to larger database systems. as it is mentioned on the access Programmers website, Microsoft access is virtually free. If your computers already have the Microsoft Office Professional Suite of business products installed that is automatically bundled as part of Microsoft Office Professional, Microsoft access is already available and there is no additional database software that is required. Support Microsoft access Support resources are available easily than any other desktop DBMS so providing support is not a difficult task. L02 Task 1 Classic SDLC Database System according to alexis Mathews (2005), different phases of DDLC are requirements analysis, database design, DBMS evaluation, selection, implementation, data loading, testing, operation, performance tuning, and maintenance. Requirements analysis Companys situation, problems and constraints are analyzed and defined. It is discussed what improvements a database management system will bring and what objectives it will help fulfill. Requirements are explicitly and granularly defined so the objectives are clear among teams of what to develop and deliver. Database Design alexis Mathews (2005) mentioned that in a database design, first a conceptual design of the database is created. In the conceptual design stage, data modeling is used to create an abstract database structure that represents the real-world scenario. Data analysis is performed. Data Items and attributes are determined. Data modeling and normalization takes place. an Entity Relationship Diagram is developed (ERD is discussed in detail in the next section). Evaluation and Selection In this phase the best suited database management system is selected and evaluated by its features, compatibility, support availability, cost and hardware requirements. Logical Design Basically, in the logical design we create a normalized ERD in which dependencies and data redundancy is minimized. Physical Design Data Dictionary is created that defines data types for attributes, indexing and parameters. Implementation It is the actual implementation of logical design through Data Definition Languages. Tables and relationships are created, different integrity constraints are applied, and indexes are defined to get an operational database ready for data storage and retrieval. Data Loading Data is loaded into the system. Testing and performance tuning Database is thoroughly tested to ensure it produces accurate results and it is optimized, if required. Maintenance This phase involves support and training. LO2 Task 2 Entity Relationship Modeling and Normalization The entity relationship model is high-level conceptual model where data is described in terms of Entities, Relationships and attributes. For the Dublin Housing Project, the entities we can infer are Housing Developments, apartment and Household Member. The relationships that we can define are: One Housing Development has Many apartments One apartment has Many Household Member living in it. attributes for each entity are defined e.g. Household Member will have attributes like Name, Date of Birth, Sex etc. The Entity relationship model of this scenario will be something like: Figure: Sample ERD for Dublin City HousingThere are several advantages and disadvantages of ER model. The conceptual design is easier to understand and is more close to the real life entities. Understanding an ER model is easier as it is more intuitive than any other form of database design. There are some disadvantages as well. If the physical database is modeled directly in line with ER model then there will be many issues like data redundancy. E.g: Each Household Member is part of a household and each household has its own set of attributes to identify itself. From the ER model given above, we can see that the Household information will be stored in the same entity record as Household Member. So there will be set of attributes that will repeat their value for all the members belonging to the same household. This will cause major integrity and consistency issues. Normalization Normalization is the process of decomposing entities into multiple related entities based on some dependency rules. The main objective is to reduce data redundancy as it can cause integrity and consistency issues. The normalized database is much more structured and easier to maintain compared to non-normalized database. E.g. In the example above, Household Member module is decomposed into two models: Household and Member where the attributes are divided logically and a relationship is added between Household and Member entities. Now the data redundancy for Household values will be removed. The basic advantage of normalization is a maintainable database design, reduced redundancy, better consistency and integrity of data. On the other hand, a special construct of Join needs to be used while querying the database for required results. If there are many decomposed tables with large quantity of data, this can cause some performance over heads. L03 Task 1 SDLC database methodology Dublin SDLC Plan Planning Phase: The main objective of this system will be to have robust storage of relevant data along with efficient retrieval and reporting schemes to assist in decision making. Data Security Data Integrity Data Retrieval Reporting MS access is to be used as the database and front end engine. For a small unit like Dublin City Housing, MS access provides ample functionality and is easy and cost effective to develop. Some basic reporting is also a part of it and that serves the purpose. analysis Phase: The following functional requirements are in place for this system: Management Housing Developments. This includes storage, retrieval, manipulation and deletion of data. Storage, Retrieval, Manipulation and Deletion of apartment related data. Management of Household Members (storage, retrieval, manipulation and deletion of data). Keeping track of household members movements from one apartment to another. Data requirements are not very complicated. Here are some of the considerations and requirements for data: Every apartment should be part of one housing development. It should be made sure that a household member is part on only one household, being part of multiple households will cause data integrity issues. Every household will occupy only one apartment at a given time. Date formats should be properly validated as incorrect formats will cause data consistency issues and will hamper filtering and reporting. Design Phase: 1. Conceptual Design: 2. Relational Schema Model: 3. Physical Design LO3 Task 2 [Database application (Forms, software application, tables etc) is submitted electronically] Queries are as follows: Query to get member and the apartment they are residing in: select member.*, apartment.* from members left join household on members.household_id = household.id left join apartments on apartments.id = household.apartment_id Query to get related apartments with one housing devlopment select * from apartments where housing_development_id = Query to see movement of household sorted by most recent movement first select mh.date_move, hh.name, from move_history mh left join household hh on hh.id = mh.household_id order by mh.date_move desc. LO3 Task 3 Suggestions The developed database system fulfills all functional requirements. Different entities can be managed easily through the forms developed. System will help decision makers to make effective decisions through analytical reporting. There are several enhancements and improvements that can be made in the system like extending it to handle rental payments for apartments, managing issues like civil works required. On the technical side, the system should be easily upgradable and extendible. It should be equipped to be able to take advantage from upgrades and improvements to core technologies, which in this case is MS access. LO3 Task 4 User Manual access information: To access particular table, click on its drop down, then find and click on table option. You will see all saved records as below: Create input forms In main menu, under Create, there is an option to create forms. You can look form in different views by just Right-clicking it. Layout view: Goto Layout view to format your form. You can apply a theme by accessing main menu Format after selecting Layout-view. Manipulate Data You can manipulate data at table-view and form-view by clicking on the field. Delete Information There are two ways to delete records. Select one/more records from table-view, right click and delete. add a new button to existing form, and sets its operation to delete. Whenever you want to delete a record, find your record by previous or next button and press DELETE. Bibliography 1. access Programmers, 2009. Management Benefits [online] available at: http://www.access-programmers.com/management-benefits.aspx [accessed 27 May 2015]. 2. alexis Mathews, 2005, Database Development Life Cycle. [online] available at: http://www.leon-leon.com/wp/2005/11/21/ddlc.html [accessed 27 May 2015]. 3. Healy, R.G., 1991 Database Management Systems. [e-book] available at: http://www.wiley.com/legacy/wileychi/gis/Volume1/BB1v1_ch18.pdf [accessed 27 May 2015].

Bleiben (To Stay) German Verb Conjugations