Rdbms Oodbms Ordbms And Xml Information Technology Essay

Rdbms Oodbms Ordbms And Xml Information Technology Essay Data modeling refers to the process where data is structured and organized. It is a key component in the field of computer science. Once data is structured, it is usually then implemented into what is called a database management system (DBMS). The main idea behind these systems to manage vast amounts of both structured and unstructured data. Unstructured data include documents, word processing, e-mail messages, pictures, and digital video and audio files. Structured data, what is needed to make a data model (via a data model theory), is found in management systems like relational databases. A data model theory is the formal description of a data model. In the development of software, the projects may focus on the design of a conceptual data model, or a logical data model. They represent two ways of describing data models. The logical description focuses on the basic features of the model, outside of any particular implementation. The physical description, on the other hand, focuses on the implementation of the particular database hosting the models features. 1.2 Data Models We can define the Data Model as a collection of concepts that can be used to describe the structure of a database, provides the necessary means to achieve this abstraction. Notice that we mean by structure of a database the data types, relationships, and constraints that should hold on the data. Most data models also include a set of basic operations for specifying retrievals and updates on the database. In addition to the basic operations provided by the data model, it is becoming more common to include concepts in the data model to specify the dynamic aspect or behavior of a database application. This allows the database designer to specify a set of valid user-defined operations that are allowed on the database objects. Database Model can be categorized according to the data structures and operators they present to the user. (1) E-R Model (2) Hierarchical Data Model (3) Network Data Model (4) Semi Structured Data Model (5) Relational Data Model (RDBMS) (6) Object Oriented Data Model (OODBMS) (7) Object Relational Data Model (ORDBMS) Among all data models mentioned below, relational model followed by object oriented and object relational models enjoyed most popularity, we are going to compare them and then we try to find out what is the relationship between XML and these relational data models. COMPARISON RDBMS, OODBMS, ORDBMS  and XML 2.1 Relational Database Management System (RDBMS) The relational model is based on the structure of a database. A database is simply a collection of one or more relations or tables with columns and rows. The use of set theory allows for data to be structured in a series of tables that has both columns and rows. Each column corresponds to an attribute of that relation, while each row corresponds to a record that contains data values for an entity. The main elements of RDBMS are based on Ted Codds 13 rules for a  relational system, the concept of relational integrity, and normalization. The three fundamentals of a relational database are that all information must be held in the form of a table, where all data are described using data values. The second fundamental is that each value found in the table columns does not repeat. The final fundamental is the use of Standard Query Language (SQL). Benefits of RDBMS are that the system is simple, flexible, and productive. Because  the tables are simple, data is easier to understand and communicate with others. RDBMS are flexible because users do not have to use predefined keys to input information. Also,  RDBMS are more productive because SQL is easier to learn. This allows users to spend more time  inputting instead of learning. More importantly, RDBMSs biggest  advantage is the simplicity with which users can  create and access data and extend it if needed. After the original database is created, new data categories can be added without the existing application being changed. There are limitations to the relational database management system. First, relational databases do not have enough storage area to handle data such as images, digital and audio/video. The system was originally created to handle the integration of media, traditional fielded data, and templates. Another limitation of the relational database is its inadequacy to operate with languages outside of SQL. After its original development, languages such as C++ and JavaScript were formed. However, relational databases do not work efficiently with these languages. A third limitation is the requirement that information must be in tables where relationships between entities are defined by values. Today, the relational model is the dominant data model as well as the foundation for the leading DBMS products, which include IBMs DB2 family, Informix, Oracle, Sybase, Microsofts Access and SQLServer. 2.3 Object Oriented Database Management (OODBMS) The main objective of Object-Oriented  Database Management Systems, commonly known as OODBMS, is to provide consistent, data independent, secure, controlled and extensible data management services to support the object-oriented model. They were created to  handle big and complex data that relational databases could not. There are important characteristics involved with object-oriented databases. The most important characteristic is the joining of object-oriented programming with database technology, which provides an integrated application development system. Object-oriented programming results in 4 main characteristics:  inheritances, data encapsulation, object identity, and polymorphism. Inheritance allows one to develop solutions to complex problems incrementally by defining new objects in terms of previously defined objects. Data encapsulation or simply encapsulation allows the hiding of the internal state of the objects. Encapsulated objects are those objects that can only be assessed by their methods instead of their internal states. There are three types of encapsulated objects users and developers should recognize. The first is full encapsulation, in which all the operations on objects are done through message sending and method execution. The second is write encapsulation, which is where the internal state of the object is visible only for reading operations. The third is partial encapsulation, which involves allowing direct access for reading and writing for only a part of the internal state. Object identity allows objects of the database to be independent of each other. Polymorphism and dynamic binding allow one to define operations for one object and then to share the specification of the operation with other objects. This allows users and/or programmers to compose objects to provide solutions without having to write code that is specific to each object. The language important to OODBMS is data definition and manipulation language (DDML). The use of this language allows persistent data to be created, updated, deleted, or retrieved. An OODBMS needs a computational versus a relational language because it can be used to avoid impedance mismatch. DDML allows users to define a database, including creating, altering, and dropping tables and establishing constraints. DDMLs are used to maintain and query a database, including updating, inserting, modifying, and querying data. The OODBMS has many advantages and benefits. First, object-oriented is a more natural way of thinking. Second, the defined operations of these types of systems are not dependent on the particular database application running at a given moment. Third, the data types of object-oriented databases can be extended to support complex data such as images, digital and audio/video, along with other multi-media operations. Different benefits of OODBMS are its reusability, stability, and  reliability. Another benefit of OODBMS is that relationships are represented explicitly, often supporting both navigational and associative access to information. This translates to improvement in data access performance versus the relational model. Another important benefit is that users are allowed to define their own methods of access to data and how it will be represented or manipulated. The most significant benefit of the OODBMS is that these databases have extended into areas not known by the RDBMS. Medicine, multimedia, and high-energy physics are just a few of the new industries relying on object-oriented databases. As with the relational database method, object-oriented databases also has disadvantages or limitations. One disadvantage of OODBMS is that it lacks a common data model. There is also no current standard, since it is still considered to be in the development stages. A significant difference between object-oriented databases and relational databases is that object-oriented databases represent relationships explicitly, supporting both navigational and associative access to information. As the complexity of interrelationships between information within the database increases, so do the  advantages of representing relationships explicitly. Another benefit of using explicit relationships is the improvement in data access performance over relational value-based relationships. 2.4 Object Relational Database Management System (ORDBMS)   Object Relational Database Management System (ORDBMS) is an extended development of existing relational database system. To overcome the certain limitations and to increase the performance level, and to achieve the benefits of relational model and object model, ORDBMS technology evolved by combining the relational databases and object oriented concepts. We can incorporate our custom data types, functions, operators and methods with the database and we can store images, geographical information and multimedia objects such as audio and video in ORDBMS. And it allows us to raise the level of abstraction at which we want to view the problem domain. In RDBMS, it is difficult to map the objects to the database whereas in OODBMS object oriented features are supported extensively. However, in ORDBMS limited support of object oriented features, mostly to new data types. Moreover, it supports abstract data types (ADTs) and complex relationships. ORDBMSs have the same query centric approach to data management as we have in RDBMS. Through declarative SQL statements, we can handle the data access and there is no procedural or object-at-a-time, navigational interface. ORDBMS allows us to continue using our existing systems, without having to make major changes. Another advantage is that it allows users and programmers to start using object-oriented systems in parallel. In ORDBMS technology the concept of extensibility is a principal innovation. ORDBMSs have an extended functionality of DBMS and information system which can be deployed over different machines as it has a central server program whereas OODBMS has a typical distributed data architecture. This is the difference in architectures of ORDBMS and OODBMS. Another difference between ORDBMS and OODBMS is, an object-oriented databases design is based solely on Object-Oriented Analysis and Design (OOAD) principles whereas ORDBMS is an extended development of traditional relational database with object oriented concepts structures such as abstract data type, nested tables, and varying arrays. In simple words, we can say that ORDBMSs synthesize the features of RDBMSs with the best ideas of OODBMSs.   Where Does Xml Fit? DBMS have advanced into the Internet and Web Age.  Stored data is widely being accessed through a Web browser. Today, queries are being generated through Web-accessible forms and answers are being formatted using a mark-up language such as HTML or XML. In addition, many vendors and distributors are adding features to their DBMS aimed at making it better equipped for Internet usage If your application requires moving data between enterprises, XML is a good solution. XML lets you send data across the Internet and through firewalls by using the standard HTTP protocol. XML is also a good choice if your application needs to move data between hardware or software platforms (OSs).  XML is not machine- or OS-specific. Finally, XML is a  good choice if you simply want to ensure that your application or data source is robust even if the data schema changes.  XML enables your application to be extensible  because you access the XML-formatted data by using element and attribute names instead of offsets, which structured programming languages use. If you have one or more of these application requirements, then XML is a good solution. 3.1 Data storage using XML XML Databases offer the same functionality of Object Databases, data is structured in a hierarchical manner and they store XML documents instead of theoretical Objects. We could even say that the XML database model is just a comeback of the hierarchical model because in principle this is the same concept of data storage, indexation and querying. XML databases have the added benefit of being able exchange the data in its native format, which is perfect for todays web requirements. 3.2 Data exchange using XML   XML  messages exchanged are by nature hierarchical and deeply tree structured, sometimes the data is even unpredictable and sometimes the structure is prone to change at any time, developers trying to map this data to a relational structure may find their lives becoming more and more difficult. XML Databases can accept structured as well as unstructured data. XML documents do not have to conform to any set Schema so a developer can fire anything they wish at the database, no need to modify tables and columns. XML Schema allows one to define an XML document in both its node structure (e.g. elements and attributes) as well as the data types contained within these nodes. It allows one to define these data types in very explicit detail. This usage has a lot of advantages, at least for front-end applications: It saves a lot of memory by removing application-specific classes and replacing it with a small set of classes, the DOM. This means that a single application server can handle a lot more of different data types. This is important to us as we designed our presentation layer for Application Service Provider (ASP) usage. The ASP context means that to keep costs as low as possible, you run many different applications in the same application server. If each application had its own set of application-specific classes to model data, the application server would be crowded with classes. It saves a lot of time and energy by the sheer flexibility of XML. If your data and application code are written in XML, adding or removing data to the presentation layer is a way much easier than if data was modelled in application-specific classes. You dont have to modify the application-specific classes, recompile the whole application and redeploy. There are of course some disadvantages, but I think its just a matter of work and time before they can be fixed: -If you dont seem to have a requirement to move data between enterprises, across the Internet, or through firewalls.  So, unless youre trying to make your applications more extensible, XML isnt a good choice for your scenario -Using XML as your database will work fine as long as your datasets stay relatively small. Meaning, it can all fit in memory and stay there comfortably. Once your data grows to the point where it will not all fit in memory, you will probably start seeing serious performance degradation -The problem for many XML aspirations is that the core of an RDBMS are its  relations. In particular, the set of constraints that exist between tables, and that are enforced by the RDBMS are what make RDBMSs so useful and powerful. XML has no inherent mechanism for enforcing constraints. -If you have a heavy investment in an Object-Relational DBMS (Oracle, MS, IBM) and have learned to live with them changing the data model in such systems from relational to anything else would entail a huge amount of work and risk. Conclusions Relational databases have a strong-hold on the current database market due to their maturity, reliability, the majority of existing applications using the relational model. As object-oriented programming languages continue emerging as the favored or dominate programming language for building new applications, probably OODMBS will surpass the RDBMS as the most popular and dominate database management systems in the business market. Something similar is happening to the object-relational database management system (ORDBMS) which the main objective is to merge the benefits of both the relational and object-oriented model. Many RDBMS products on the market today are releasing first generation ORDBMS products. If these products are able to fulfill the main objective of ORDBMS as well as enable companies to convert existing relational models to partial or full object-oriented models, the end of relational databases could be eminent. The growth in popularity of XML has been almost as dramat ic as that of OO. As a consequence, new standards for data objects and new development products based on XML keep emerging. In my opinion the main reason why RDBMS Data Model dominates the market right now is because RDBMS design has evolved to disallow users from asking questions that the database isnt good at answering. The fact that we ship databases that only permit things that we know how to answer efficiently does NOT imply that we will never be able to answer other questions more efficiently. It is quite easy to see a trend in the industry that shows consistent continual progress at solving hard query problems. Of course some problems will always be hard (distributed cost-based query optimization is one), but I would point out that research on RDBMS optimizations has tapered off quite a bit and we have seen major increases in research geared towards semi-structured data. So we are simply easing off on some of the traditional RDBMS constraints and beginning to allow things like recursive self-joins, ragged hierarchies, etc. and we are optimizing these things. I mean, we already solved the RDBMs opti mization challenge and now it is time to move to the next thing. XML seems like a very appropriate evolutionary step.

Benefits and Features of Excel

Excel is a spreadsheet program. Microsoft Excel is written and distributed by Microsoft. It is used mainly in computers that uses Microsoft Windows operating system or Apple Macintosh computers. It features an intuitive interface and capable calculation and graphing tools. Because of aggressive marketing, Microsoft has made Excel one of the most popular spreadsheet applications that are used these days. It is the dominant spreadsheet application available for Microsoft Windows and Apple Macintosh platforms. The latest releaseof Excel is Microsoft Office 2007 Excel (beta version).Benefits and Features of Excel In Excel user can run queries to sort and filter data, as well as user can run complicated calculations to derive the information they want. One important feature that Excel contains is use of Microsoft PivotTable and Microsoft PivotChart views to work with data interactively. Both uses forms to add, update, delete and navigate user data. Excel is capable of report generations o n data and view in multiple formats. One of the important features Excel contains is to connect to external data and view, query, and edit it without having to import.Excel can imports data form external databases and also capable of export of data too. Excel can create web pages to display data as read-only or to access it in an updatable format and can create a Microsoft Word mail merge (Nelson 2006). Microsoft Excel organizes data in columns. Columns are also called as fields and store a particular kind of information, or data type. At the top of each column, the first cell is used to label the column. Excel is used in the cases when the data is flat. Suppose user has to create a report only once from a set of data, then in this case Excel will be preferred.Second case is when the relationships is not going to change, this means that the structure of the data will remains same so Excel can be used in this case. Another case when Excel can be used is when the report format of the data is not going to change (Kevin 2006). Below is the summary of the cases when the data should be stored in Excel: †¢ If there is a requirement of a flat or non-relational view of data †¢ If the data is mostly numeric. †¢ If user want to run primarily calculations and statistical comparisons on data.†¢ If the dataset is manageable in size (not more than 15,000 rows). (Nelson 2006) References: Nelson, E. 2006. ‘Using Access or Excel to manage your data'. Retrieved on 29 November 2006 from http://office. microsoft. com/en-us/help/HA010429181033. aspx Microsoft Excel. Retrieved on 29 November 2006 from http://en. wikipedia. org/wiki/Microsoft_Excel Kevin 2006. ‘Access Vs. Excel: When to Use Excel'. Retrieved on 29 November 2006 from http://www. workplacelife. com/2006/05/09/access-vs-excel-when-to-use-excel/

The Influences Of Mass Media On Society - 864 Words

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Baseball The Greatest Past Times - 1079 Words

Baseball, known as one of America’s greatest past times, has such an iconic and diverse history. From the founding of the game, to the struggles and historic events, and even the many great players, baseball is filled with so much history that has made professional baseball what it is today. The 19th century was an integral time in the evolution of baseball. The game of baseball saw a great amount of growth, exciting ballplayers, and the creation of professional teams that would eventually soon become known as Major League Baseball, MLB. The game of baseball had been around for quite some time with several different rules and regulations determined by those playing. In enters Alexander Joy Cartwright, who would develop major rules in†¦show more content†¦Due to the nature of baseball, it could be played on virtually any surface. And although most clubs were perceivably owned by the upper class, during the mid 19th century, baseball grew among the working class who bec ame players and was the most popular among fans of the game. The surges in playing also saw the expansion of clubs and teams towards the north, and eventually move westward towards Oregon and California. In 1869, after many more clubs formed, the first publicly announced all-professional baseball team was formed. The Cincinnati Red Stockings, formed under the leadership of captain Harry Wright, was the first team to put players under contract and pay them a salary. The team was financed by a group of Ohio investors and Wright recruited players from all over the country and had them undergo rigorous training and practice. The training was merited as the team traveled from coast to coast winning all of their games and recorded the only undefeated season in baseball history. Shortly after, the team would suffer financially and the team folded after only two years (Legend of the Cincinnati Red Stockings). Nevertheless, although the Cincinnati team folded, the popularity of baseball had grown so big that the team set a precedent for future professional teams to follow. These teams would join the professional ranks and create The National Association of